Dr David AB Dance

Research Area: Microbiology
Scientific Themes: Tropical Medicine & Global Health and Immunology & Infectious Disease
Keywords: Melioidosis, Burkholderia pseudomallei
Web Links:
Worldwide distribution of melioidosis (from Currie, Dance & Cheng, Transactions of the Royal Society of Tropical Medicine and Hygiene 2008)

Worldwide distribution of melioidosis (from Currie, Dance & Cheng, Transactions of the Royal ...

B. pseudomallei growing on Ashdown's agar

B. pseudomallei growing on Ashdown's agar

Rice farmers in Thailand - a group at risk of melioidosis

Rice farmers in Thailand - a group at risk of melioidosis

David Dance is a Clinical Microbiologist supporting the work of LOMWRU (Lao-Oxford-Mahosot Hospital Wellcome Research Unit) on bacterial infections of importance to public health in Laos.

He is particularly interested in all aspects of melioidosis (Burkholderia pseudomallei infection), especially gaining a greater understanding of the global distribution of the disease and the environmental factors that underpin its distribution.

Other interests include:

  • aetiology of bacteraemia, pneumonia, meningitis and endocarditis
  • antimicrobial resistance
  • typhoid and other Salmonella and Shigella infections
  • streptococcal infections, including pneumococci, Strep. suis and and Group A streptococci.

Name Department Institution Country
Dr Sabine Dittrich Tropical Medicine Oxford University, Vientiane Laos
Professor Nicholas PJ Day FMedSci FRCP Tropical Medicine Oxford University, Bangkok Thailand
Professor Jeremy Day Tropical Medicine Oxford University, Ho Chi Minh City Vietnam
Dr Rory Bowden Wellcome Trust Centre for Human Genetics Oxford University, Henry Wellcome Building of Genomic Medicine United Kingdom
Professor Derrick Crook Experimental Medicine Division Oxford University, John Radcliffe Hospital United Kingdom
Dr Nicole Stoesser Experimental Medicine Division Oxford University, John Radcliffe Hospital United Kingdom
Professor Sir Nicholas J White FRS Tropical Medicine Oxford University, Bangkok Thailand
Professor Paul Turner Tropical Medicine Oxford University, Siem Reap Cambodia
Professor Stephen Baker Tropical Medicine Oxford University, Ho Chi Minh City Vietnam
Dr Direk Limmathurotsakul Tropical Medicine Oxford University, Bangkok Thailand
Professor Paul Newton Tropical Medicine Oxford University, Vientiane Laos
Professor Sharon Peacock London School of Hygiene and Tropical Medicine United Kingdom
Bart Currie Menzies School of Health Research Menzies School of Health Research Australia
Ivo Steinmetz University of Greifswald Germany
Associate Professor Fiona Russell University of Melbourne Australia
Dr Pierre Smeesters University of Melbourne Australia
Dr Esther Kuenzli Medical Services and Diagnostics Swiss Tropical and Public Health Institute Switzerland
Dr David Aucoin Microbiology and Immunology University of Nevada United States
Ashley EA, Recht J, Chua A, Dance D, Dhorda M, Thomas NV, Ranganathan N, Turner P, Guerin PJ, White NJ, Day NP. 2018. An inventory of supranational antimicrobial resistance surveillance networks involving low- and middle-income countries since 2000. J Antimicrob Chemother, | Show Abstract | Read more

Low- and middle-income countries (LMICs) shoulder the bulk of the global burden of infectious diseases and drug resistance. We searched for supranational networks performing antimicrobial resistance (AMR) surveillance in LMICs and assessed their organization, methodology, impacts and challenges. Since 2000, 72 supranational networks for AMR surveillance in bacteria, fungi, HIV, TB and malaria have been created that have involved LMICs, of which 34 are ongoing. The median (range) duration of the networks was 6 years (1-70) and the number of LMICs included was 8 (1-67). Networks were categorized as WHO/governmental (n = 26), academic (n = 24) or pharma initiated (n = 22). Funding sources varied, with 30 networks receiving public or WHO funding, 25 corporate, 13 trust or foundation, and 4 funded from more than one source. The leading global programmes for drug resistance surveillance in TB, malaria and HIV gather data in LMICs through periodic active surveillance efforts or combined active and passive approaches. The biggest challenges faced by these networks has been achieving high coverage across LMICs and complying with the recommended frequency of reporting. Obtaining high quality, representative surveillance data in LMICs is challenging. Antibiotic resistance surveillance requires a level of laboratory infrastructure and training that is not widely available in LMICs. The nascent Global Antimicrobial Resistance Surveillance System (GLASS) aims to build up passive surveillance in all member states. Past experience suggests complementary active approaches may be needed in many LMICs if representative, clinically relevant, meaningful data are to be obtained. Maintaining an up-to-date registry of networks would promote a more coordinated approach to surveillance.

Dance D, Limmathurotsakul D. 2018. Global Burden and Challenges of Melioidosis Tropical Medicine and Infectious Disease, 3 (1), pp. 13-13. | Read more

Dittrich S, Boudthasavong L, Keokhamhoung D, Phuklia W, Craig SB, Tulsiani SM, Burns M-A, Weier SL, Dance DAB, Davong V et al. 2018. A Prospective Hospital Study to Evaluate the Diagnostic Accuracy of Rapid Diagnostic Tests for the Early Detection of Leptospirosis in Laos. Am J Trop Med Hyg, | Show Abstract | Read more

Leptospirosis is a globally important cause of acute febrile illness, and a common cause of non-malarial fever in Asia, Africa, and Latin America. Simple rapid diagnostic tests (RDTs) are needed to enable health-care workers, particularly in low resource settings, to diagnose leptospirosis early and give timely targeted treatment. This study compared four commercially available RDTs to detect human IgM againstLeptospiraspp. in a head-to-head prospective evaluation in Mahosot Hospital, Lao PDR. Patients with an acute febrile illness consistent with leptospirosis (N= 695) were included in the study during the 2014 rainy season. Samples were tested with four RDTs: ("Test-it" [Life Assay, South Africa;N= 418]; "Leptorapide" [Linnodee, Northern Ireland;N= 492]; "Dual Path Platform" [DPP] [Chembio;N= 530]; and "SD-IgM" [Standard Diagnostics, South Korea;N= 481]). Diagnostic performance characteristics were calculated and compared with a composite reference standard combining PCR (rrs), microscopic agglutination tests (MATs), and culture. Of all patients investigated, 39/695 (5.6%) were positive by culture, PCR, or MAT. The sensitivity and specificity of the RDTs ranged greatly from 17.9% to 63.6% and 62.1% to 96.8%, respectively. None of the investigated RDTs reached a sensitivity or specificity of > 90% for detectingLeptospirainfections on admission. In conclusion, our investigation highlights the challenges associated withLeptospiradiagnostics, particularly in populations with multiple exposures. These findings emphasize the need for extensive prospective evaluations in multiple endemic settings to establish the value of rapid tools for diagnosing fevers to allow targeted antibiotics.

Wiersinga WJ, Virk HS, Torres AG, Currie BJ, Peacock SJ, Dance DAB, Limmathurotsakul D. 2018. Melioidosis. Nat Rev Dis Primers, 4 pp. 17107. | Show Abstract | Read more

Burkholderia pseudomallei is a Gram-negative environmental bacterium and the aetiological agent of melioidosis, a life-threatening infection that is estimated to account for ∼89,000 deaths per year worldwide. Diabetes mellitus is a major risk factor for melioidosis, and the global diabetes pandemic could increase the number of fatalities caused by melioidosis. Melioidosis is endemic across tropical areas, especially in southeast Asia and northern Australia. Disease manifestations can range from acute septicaemia to chronic infection, as the facultative intracellular lifestyle and virulence factors of B. pseudomallei promote survival and persistence of the pathogen within a broad range of cells, and the bacteria can manipulate the host's immune responses and signalling pathways to escape surveillance. The majority of patients present with sepsis, but specific clinical presentations and their severity vary depending on the route of bacterial entry (skin penetration, inhalation or ingestion), host immune function and bacterial strain and load. Diagnosis is based on clinical and epidemiological features as well as bacterial culture. Treatment requires long-term intravenous and oral antibiotic courses. Delays in treatment due to difficulties in clinical recognition and laboratory diagnosis often lead to poor outcomes and mortality can exceed 40% in some regions. Research into B. pseudomallei is increasing, owing to the biothreat potential of this pathogen and increasing awareness of the disease and its burden; however, better diagnostic tests are needed to improve early confirmation of diagnosis, which would enable better therapeutic efficacy and survival.

Darton TC, Tuyen HT, The HC, Newton PN, Dance DAB, Phetsouvanh R, Davong V, Campbell JI, Hoang NVM, Thwaites GE et al. 2018. Azithromycin Resistance in Shigella spp. in Southeast Asia. Antimicrob Agents Chemother, 62 (4), | Show Abstract | Read more

Infection by Shigella spp. is a common cause of dysentery in Southeast Asia. Antimicrobials are thought to be beneficial for treatment; however, antimicrobial resistance in Shigella spp. is becoming widespread. We aimed to assess the frequency and mechanisms associated with decreased susceptibility to azithromycin in Southeast Asian Shigella isolates and use these data to assess appropriate susceptibility breakpoints. Shigella isolates recovered in Vietnam and Laos were screened for susceptibility to azithromycin (15 μg) by disc diffusion and MIC. Phenotypic resistance was confirmed by PCR amplification of macrolide resistance loci. We compared the genetic relationships and plasmid contents of azithromycin-resistant Shigella sonnei isolates using whole-genome sequences. From 475 available Shigella spp. isolated in Vietnam and Laos between 1994 and 2012, 6/181 S. flexneri isolates (3.3%, MIC ≥ 16 g/liter) and 16/294 S. sonnei isolates (5.4%, MIC ≥ 32 g/liter) were phenotypically resistant to azithromycin. PCR amplification confirmed a resistance mechanism in 22/475 (4.6%) isolates (mphA in 19 isolates and ermB in 3 isolates). The susceptibility data demonstrated the acceptability of the S. flexneri (MIC ≥ 16 g/liter, zone diameter ≤ 15 mm) and S. sonnei (MIC ≥ 32 g/liter, zone diameter ≤ 11 mm) breakpoints with a <3% discrepancy. Phylogenetic analysis demonstrated that decreased susceptibility has arisen sporadically in Vietnamese S. sonnei isolates on at least seven occasions between 2000 and 2009 but failed to become established. While the proposed susceptibility breakpoints may allow better recognition of resistant isolates, additional studies are required to assess the impact on the clinical outcome. The potential emergence of azithromycin resistance highlights the need for alternative options for management of Shigella infections in countries where Shigella is endemic.

Hantrakun V, Thaipadungpanit J, Rongkard P, Srilohasin P, Amornchai P, Langla S, Mukaka M, Chantratita N, Wuthiekanun V, Dance DAB et al. 2018. Presence of B. thailandensis and B. thailandensis expressing B. pseudomallei-like capsular polysaccharide in Thailand, and their associations with serological response to B. pseudomallei. PLoS Negl Trop Dis, 12 (1), pp. e0006193. | Show Abstract | Read more

BACKGROUND: Burkholderia pseudomallei is an environmental Gram-negative bacillus and the cause of melioidosis. B. thailandensis, some strains of which express a B. pseudomallei-like capsular polysaccharide (BTCV), is also commonly found in the environment in Southeast Asia but is considered non-pathogenic. The aim of the study was to determine the distribution of B. thailandensis and its capsular variant in Thailand and investigate whether its presence is associated with a serological response to B. pseudomallei. METHODOLOGY/PRINCIPAL FINDINGS: We evaluated the presence of B. pseudomallei and B. thailandensis in 61 rice fields in Northeast (n = 21), East (n = 19) and Central (n = 21) Thailand. We found BTCV in rice fields in East and Central but not Northeast Thailand. Fourteen fields were culture positive for B. pseudomallei alone, 8 for B. thailandensis alone, 11 for both B. pseudomallei and B. thailandensis, 6 for both B. thailandensis and BTCV, and 5 for B. pseudomallei, B. thailandensis and BTCV. Serological testing using the indirect hemagglutination assay (IHA) of 96 farmers who worked in the study fields demonstrated that farmers who worked in B. pseudomallei-positive fields had higher IHA titers than those who worked in B. pseudomallei-negative fields (median 1:40 [range: <1:10-1:640] vs. <1:10 [range: <1:10-1:320], p = 0.002). In a multivariable ordered logistic regression model, IHA titers were significantly associated with the presence of B. pseudomallei (aOR = 3.7; 95% CI 1.8-7.8, p = 0.001) but were not associated with presence of B. thailandensis (p = 0.32) or BTCV (p = 0.32). One sequence type (696) was identified for the 27 BTCV isolates tested. CONCLUSIONS/SIGNIFICANCE: This is the first report of BTCV in Thailand. The presence of B. pseudomallei and B. thailandensis in the same field was not uncommon. Our findings suggest that IHA positivity of healthy rice farmers in Thailand is associated with the presence of B. pseudomallei in rice fields rather than B. thailandensis or BTCV.

Le Thi Phuong T, Rattanavong S, Vongsouvath M, Davong V, Phu Huong Lan N, Campbell JI, Darton TC, Thwaites GE, Newton PN, Dance DAB, Baker S. 2017. Non-typhoidal Salmonella serovars associated with invasive and non-invasive disease in the Lao People's Democratic Republic. Trans R Soc Trop Med Hyg, 111 (9), pp. 418-424. | Show Abstract | Read more

Background: Invasive non-typhoidal Salmonella (iNTS) disease is a well-described cause of mortality in children and human immunodeficiency virus (HIV)-infected adults in sub-Saharan Africa. Additionally, there is an ill-defined burden of iNTS disease in Southeast Asia. Methods: Aiming to investigate the causative serovars of non-invasive and iNTS disease and their associated antimicrobial susceptibility profiles in the Lao People's Democratic Republic, we performed multilocus sequence typing and antimicrobial susceptibility profiling on 168 NTS (63 blood and 105 faecal) organisms isolated in Lao between 2000 and 2012. Results: Six different serovars were isolated from blood; Salmonella enterica serovar Enteritidis (n=28), S. enterica serovar Typhimurium (n=19) and S. enterica serovar Choleraesuis (n=11) accounted for >90% (58/63) of the iNTS disease cases. In contrast, the isolates from diarrhoeal faeces were comprised of 18 different serovars, the mostly commonly identified being S. enterica Typhimurium (n=28), S. enterica Weltevreden (n=14) and S. enterica Stanley (n=15). S. enterica Enteritidis and S. enterica Choleraesuis were significantly more associated with systemic disease than diarrhoeal disease in this patient group (p<0.001). Conclusions: We find a differing distribution of Salmonella sequence types/serovars between those causing iNTS disease and non-invasive disease in Lao. We conclude that there is a small but not insignificant burden of iNTS disease in Lao. Further clinical and epidemiological investigations are required to assess mortality and the role of comorbidities such as HIV.

Ombelet S, Ronat JB, Walsh T, Yansouni CP, Cox J, Vlieghe E, Martiny D, Semret M, Vandenberg O, Jacobs J et al. 2018. Clinical bacteriology in low-resource settings: today's solutions The Lancet Infectious Diseases, | Show Abstract | Read more

© 2018 Elsevier Ltd Low-resource settings are disproportionately burdened by infectious diseases and antimicrobial resistance. Good quality clinical bacteriology through a well functioning reference laboratory network is necessary for effective resistance control, but low-resource settings face infrastructural, technical, and behavioural challenges in the implementation of clinical bacteriology. In this Personal View, we explore what constitutes successful implementation of clinical bacteriology in low-resource settings and describe a framework for implementation that is suitable for general referral hospitals in low-income and middle-income countries with a moderate infrastructure. Most microbiological techniques and equipment are not developed for the specific needs of such settings. Pending the arrival of a new generation diagnostics for these settings, we suggest focus on improving, adapting, and implementing conventional, culture-based techniques. Priorities in low-resource settings include harmonised, quality assured, and tropicalised equipment, consumables, and techniques, and rationalised bacterial identification and testing for antimicrobial resistance. Diagnostics should be integrated into clinical care and patient management; clinically relevant specimens must be appropriately selected and prioritised. Open-access training materials and information management tools should be developed. Also important is the need for onsite validation and field adoption of diagnostics in low-resource settings, with considerable shortening of the time between development and implementation of diagnostics. We argue that the implementation of clinical bacteriology in low-resource settings improves patient management, provides valuable surveillance for local antibiotic treatment guidelines and national policies, and supports containment of antimicrobial resistance and the prevention and control of hospital-acquired infections.

Phouangsouvanh S, Mayxay M, Keoluangkhot V, Vongsouvath M, Davong V, Dance DAB. 2017. Antibiotic susceptibility of Neisseria gonorrhoeae in Vientiane, Lao PDR Journal of Global Antimicrobial Resistance, | Read more

Woods K, Nic-Fhogartaigh C, Arnold C, Boutthasavong L, Phuklia W, Lim C, Chanthongthip A, Tulsiani SM, Craig SB, Burns M-A et al. 2017. A comparison of two molecular methods for diagnosing leptospirosis from three different sample types in patients presenting with fever in Laos. Clin Microbiol Infect, | Show Abstract | Read more

OBJECTIVES: To compare two molecular assays (rrs quantitative PCR (qPCR) versus a combined 16SrRNA and LipL32 qPCR) on different sample types for diagnosing leptospirosis in febrile patients presenting to Mahosot Hospital, Vientiane, Laos. METHODS: Serum, buffy coat and urine samples were collected on admission, and follow-up serum ∼10 days later. Leptospira spp. culture and microscopic agglutination tests (MAT) were performed as reference standards. Bayesian latent class modelling was performed to estimate sensitivity and specificity of each diagnostic test. RESULTS: In all, 787 patients were included in the analysis: 4/787 (0.5%) were Leptospira culture positive, 30/787 (3.8%) were MAT positive, 76/787 (9.7%) were rrs qPCR positive and 20/787 (2.5%) were 16SrRNA/LipL32 qPCR positive for pathogenic Leptospira spp. in at least one sample. Estimated sensitivity and specificity (with 95% CI) of 16SrRNA/LipL32 qPCR on serum (53.9% (33.3%-81.8%); 99.6% (99.2%-100%)), buffy coat (58.8% (34.4%-90.9%); 99.9% (99.6%-100%)) and urine samples (45.0% (27.0%-66.7%); 99.6% (99.3%-100%)) were comparable with those of rrs qPCR, except specificity of 16SrRNA/LipL32 qPCR on urine samples was significantly higher (99.6% (99.3%-100%) vs. 92.5% (92.3%-92.8%), p <0.001). Sensitivities of MAT (16% (95% CI 6.3%-29.4%)) and culture (25% (95% CI 13.3%-44.4%)) were low. Mean positive Cq values showed that buffy coat samples were more frequently inhibitory to qPCR than either serum or urine (p <0.001). CONCLUSIONS: Serum and urine are better samples for qPCR than buffy coat, and 16SrRNA/LipL32 qPCR performs better than rrs qPCR on urine. Quantitative PCR on admission is a reliable rapid diagnostic tool, performing better than MAT or culture, with significant implications for clinical and epidemiological investigations of this global neglected disease.

Teerawattanasook N, Tauran PM, Teparrukkul P, Wuthiekanun V, Dance DAB, Arif M, Limmathurotsakul D. 2017. Capacity and Utilization of Blood Culture in Two Referral Hospitals in Indonesia and Thailand. Am J Trop Med Hyg, 97 (4), pp. 1257-1261. | Show Abstract | Read more

It is generally recommended that sepsis patients should have at least two blood cultures obtained before antimicrobial therapy. From 1995 to 2015, the number of blood cultures taken each year in a 1,100-bed public referral hospital in Ubon Ratchathani northeast Thailand rose from 5,235 to 56,719, whereas the number received in an 840-bed referral public hospital in South Sulawesi, Indonesia, in 2015 was 2,779. The proportion of patients sampled for blood cultures out of all inpatients in South Sulawesi in 2015 (9%; 2,779/30,593) was lower than that in Ubon Ratchathani in 2003 (13%; 8,707/66,515), at a time when health expenditure per capita in the two countries was comparable. Under-use of bacterial cultures may lead to an underestimate and underreporting of the incidence of antimicrobial-resistant infections. Raising capacity and utilization of clinical microbiology laboratories in developing countries, at least at sentinel hospitals, to monitor the antimicrobial resistance situation should be prioritized.

Cheong E, Roberts T, Rattanavong S, Riley TV, Newton PN, Dance DAB. 2017. Clostridium difficile infection in the Lao People's Democratic Republic: first isolation and review of the literature. BMC Infect Dis, 17 (1), pp. 635. | Show Abstract | Read more

BACKGROUND: Current knowledge of the epidemiology of Clostridium difficile infection in Asia, and in particular the Greater Mekong Subregion, is very limited. Only a few studies from Thailand and Vietnam have been reported from the region with variable testing methods and results, and no studies from Lao People's Democratic Republic (PDR). Therefore we investigated the presence of C. difficile in a single centre in the Lao PDR and determined the ribotypes present. METHOD: Seventy unformed stool samples from hospital inpatients at Mahosot Hospital, Vientiane, were tested for the presence of C. difficile using selective differential agar and confirmed by latex agglutination. C. difficile isolates were further characterised by ribotyping and toxin gene detection. RESULTS: C. difficile was isolated from five of the 70 patients, and five different ribotypes were identified (014, 017, 020, QX 107 and QX 574). CONCLUSION: This is the first isolation of C. difficile from human stool samples in the Lao PDR. These results will add to the limited amount of data on C. difficile in the region. In addition, we hope this information will alert clinicians to the presence of C. difficile in the country and will help inform future investigations into the epidemiology and diagnosis of C. difficile in Lao PDR.

Nguyen VH, Dubot-Pérès A, Russell FM, Dance DAB, Vilivong K, Phommachan S, Syladeth C, Lai J, Lim R, Morpeth M et al. 2017. Acute respiratory infections in hospitalized children in Vientiane, Lao PDR - the importance of Respiratory Syncytial Virus. Sci Rep, 7 (1), pp. 9318. | Show Abstract | Read more

The Human respiratory syncytial virus (RSV) is one of the most important viral pathogens, causing epidemics of acute respiratory infection (ARI), especially bronchiolitis and pneumonia, in children worldwide. To investigate the RSV burden in Laos, we conducted a one-year study in children <5 years old admitted to Mahosot Hospital, Vientiane Capital, to describe clinical and epidemiological characteristics and predictive factors for severity of RSV-associated ARI. Pooled nasal and throat swabs were tested using multiplex real-time PCR for 33 respiratory pathogens (FTD®kit). A total of 383 patients were included, 277 (72.3%) of whom presented with pneumonia. 377 (98.4%) patients were positive for at least one microorganism, of which RSV was the most common virus (41.0%), with a peak observed between June and September, corresponding to the rainy season. Most RSV inpatients had pneumonia (84.1%), of whom 35% had severe pneumonia. Children <3-months old were a high-risk group for severe pneumonia, independently of RSV infection. Our study suggests that RSV infection is frequent in Laos and commonly associated with pneumonia in hospitalized young children. Further investigations are required to provide a better overall view of the Lao nationwide epidemiology and public health burden of RSV infection over time.

Yeap AD, Woods K, Dance DAB, Pichon B, Rattanavong S, Davong V, Phetsouvanh R, Newton PN, Shetty N, Kearns AM. 2017. Molecular Epidemiology ofStaphylococcus aureusSkin and Soft Tissue Infections in the Lao People's Democratic Republic. Am J Trop Med Hyg, 97 (2), pp. 423-428. | Show Abstract | Read more

This is the first report of the molecular epidemiology ofStaphylococcus aureusfrom skin and soft tissue infections (SSTI) in Laos. We selected a random sample of 96S. aureusSSTI isolates received by the Microbiology Laboratory, Mahosot Hospital, Vientiane, between July 2012 and June 2014, including representation from seven referral hospitals. Isolates underwent susceptibility testing by Clinical and Laboratory Standards Institute methods,spatyping and DNA microarray analysis, with whole genome sequencing for rare lineages. Median patient age was 19.5 years (interquartile range 2-48.5 years); 52% (50) were female. Forty-threespatypes, representing 17 lineages, were identified. Fifty-eight percent (56) of all isolates encoded Panton-Valentine leukocidin (PVL), representing six lineages: half of these patients had abscesses and three had positive blood cultures. The dominant lineage was CC121 (39; 41%); all but one isolate encoded PVL and 49% (19) were from children under five.Staphyococcus argenteuswas identified in six (6%) patients; mostly adults > 50 years and with diabetes. Six isolates (6%) belonged to rare lineage ST2885; two possibly indicate cross-infection in a neonatal unit. One isolate from a previously undescribed lineage, ST1541, was identified. Antibiotic resistance was uncommon except for penicillin (93; 97%) and tetracycline (48; 50%). Seven (7%) isolates were methicillin-resistantS. aureus(MRSA), belonging to ST239-MRSA-III, CC59-MRSA-V(T) Taiwan Clone, ST2250-MRSA-IV, ST2885-MRSA-V and CC398-MRSA-V. Globally widespread CC5 and CC30 were absent. There are parallels inS. aureusmolecular epidemiology between Laos and neighboring countries and these data highlight the prominence of PVL and suggest infiltration of MRSA clones of epidemic potential from surrounding countries.

Manivanh L, Pierret A, Rattanavong S, Kounnavongsa O, Buisson Y, Elliott I, Maeght J-L, Xayyathip K, Silisouk J, Vongsouvath M et al. 2017. Burkholderia pseudomallei in a lowland rice paddy: seasonal changes and influence of soil depth and physico-chemical properties. Sci Rep, 7 (1), pp. 3031. | Show Abstract | Read more

Melioidosis, a severe infection with the environmental bacterium Burkholderia pseudomallei, is being recognised increasingly frequently. What determines its uneven distribution within endemic areas is poorly understood. We cultured soil from a rice field in Laos for B. pseudomallei at different depths on 4 occasions over a 13-month period. We also measured physical and chemical parameters in order to identify associated characteristics. Overall, 195 of 653 samples (29.7%) yielded B. pseudomallei. A higher prevalence of B. pseudomallei was found at soil depths greater than the 30 cm currently recommended for B. pseudomallei environmental sampling. B. pseudomallei was associated with a high soil water content and low total nitrogen, carbon and organic matter content. Our results suggested that a sampling grid of 25 five metre square quadrats (i.e. 25 × 25 m) should be sufficient to detect B. pseudomallei at a given location if samples are taken at a soil depth of at least 60 cm. However, culture of B. pseudomallei in environmental samples is difficult and liable to variation. Future studies should both rely on molecular approaches and address the micro-heterogeneity of soil when investigating physico-chemical associations with the presence of B. pseudomallei.

Douangngeun B, Theppangna W, Phommachanh P, Chomdara K, Phiphakhavong S, Khounsy S, Mukaka M, Dance DAB, Blacksell SD. 2017. Rabies surveillance in dogs in Lao PDR from 2010-2016. PLoS Negl Trop Dis, 11 (6), pp. e0005609. | Show Abstract | Read more

BACKGROUND: Rabies is a fatal viral disease that continues to threaten both human and animal health in endemic countries. The Lao People's Democratic Republic (Lao PDR) is a rabies-endemic country in which dogs are the main reservoir and continue to present health risks for both human and animals throughout the country. METHODS: Passive, laboratory-based rabies surveillance was performed for suspected cases of dog rabies in Vientiane Capital during 2010-2016 and eight additional provinces between 2015-2016 using the Direct Fluorescent Antibody Test (DFAT). RESULTS: There were 284 rabies positive cases from 415 dog samples submitted for diagnosis. 257 cases were from Vientiane Capital (2010-2016) and the remaining 27 cases were submitted during 2015-2016 from Champassak (16 cases), Vientiane Province (4 cases), Xieng Kuang (3 cases), Luang Prabang (2 cases), Saravan (1 case), Saisomboun (1 case) and Bokeo (1 case). There was a significant increase in rabies cases during the dry season (p = 0.004) (November to April; i.e., <100mm of rainfall per month). No significant differences were noted between age, sex, locality of rabies cases. CONCLUSION: The use of laboratory-based rabies surveillance is a useful method of monitoring rabies in Lao PDR and should be expanded to other provincial centers, particularly where there are active rabies control programs.

Suttisunhakul V, Pumpuang A, Ekchariyawat P, Wuthiekanun V, Elrod MG, Turner P, Currie BJ, Phetsouvanh R, Dance DAB, Limmathurotsakul D et al. 2017. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the identification of Burkholderia pseudomallei from Asia and Australia and differentiation between Burkholderia species. PLoS One, 12 (4), pp. e0175294. | Show Abstract | Read more

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly used for rapid bacterial identification. Studies of Burkholderia pseudomallei identification have involved small isolate numbers drawn from a restricted geographic region. There is a need to expand the reference database and evaluate B. pseudomallei from a wider geographic distribution that more fully captures the extensive genetic diversity of this species. Here, we describe the evaluation of over 650 isolates. Main spectral profiles (MSP) for 26 isolates of B. pseudomallei (N = 5) and other Burkholderia species (N = 21) were added to the Biotyper database. MALDI-TOF MS was then performed on 581 B. pseudomallei, 19 B. mallei, 6 B. thailandensis and 23 isolates representing a range of other bacterial species. B. pseudomallei originated from northeast and east Thailand (N = 524), Laos (N = 12), Cambodia (N = 14), Hong Kong (N = 4) and Australia (N = 27). All 581 B. pseudomallei were correctly identified, with 100% sensitivity and specificity. Accurate identification required a minimum inoculum of 5 x 107 CFU/ml, and identification could be performed on spiked blood cultures after 24 hours of incubation. Comparison between a dendrogram constructed from MALDI-TOF MS main spectrum profiles and a phylogenetic tree based on recA gene sequencing demonstrated that MALDI-TOF MS distinguished between B. pseudomallei and B. mallei, while the recA tree did not. MALDI-TOF MS is an accurate method for the identification of B. pseudomallei, and discriminates between this and other related Burkholderia species.

Dance DAB, Limmathurotsakul D, Currie BJ. 2017. Burkholderia pseudomallei: Challenges for the clinical microbiology laboratory-A response from the front line Journal of Clinical Microbiology, 55 (3), pp. 980-982. | Read more

Dance DAB, Limmathurotsakul D, Currie BJ. 2017. Burkholderia pseudomallei: Challenges for the Clinical Microbiology Laboratory-a Response from the Front Line. J Clin Microbiol, 55 (3), pp. 980-982. | Read more

Chewapreecha C, Holden MTG, Vehkala M, Välimäki N, Yang Z, Harris SR, Mather AE, Tuanyok A, De Smet B, Le Hello S et al. 2017. Global and regional dissemination and evolution of Burkholderia pseudomallei. Nat Microbiol, 2 (4), pp. 16263. | Show Abstract | Read more

The environmental bacterium Burkholderia pseudomallei causes an estimated 165,000 cases of human melioidosis per year worldwide and is also classified as a biothreat agent. We used whole genome sequences of 469 B. pseudomallei isolates from 30 countries collected over 79 years to explore its geographic transmission. Our data point to Australia as an early reservoir, with transmission to Southeast Asia followed by onward transmission to South Asia and East Asia. Repeated reintroductions were observed within the Malay Peninsula and between countries bordered by the Mekong River. Our data support an African origin of the Central and South American isolates with introduction of B. pseudomallei into the Americas between 1650 and 1850, providing a temporal link with the slave trade. We also identified geographically distinct genes/variants in Australasian or Southeast Asian isolates alone, with virulence-associated genes being among those over-represented. This provides a potential explanation for clinical manifestations of melioidosis that are geographically restricted.

Dance D. 2016. Melioidosis parotitis in children. J Venom Anim Toxins Incl Trop Dis, 22 (1), pp. 33. | Show Abstract | Read more

A recent paper published inJVATiTDreporting a child in Hainan with parotitis caused byBurkholderia pseudomalleimisleadingly described parotitis as a rare manifestation of melioidosis. In fact, it is one of the commonest forms of paediatric melioidosis seen in other parts of Southeast Asia, although interestingly not in Australia.

Turner P, Kloprogge S, Miliya T, Soeng S, Tan P, Sar P, Yos P, Moore CE, Wuthiekanun V, Limmathurotsakul D et al. 2016. A retrospective analysis of melioidosis in Cambodian children, 2009-2013. BMC Infect Dis, 16 (1), pp. 688. | Show Abstract | Read more

BACKGROUND: Melioidiosis, infection by Burkholderia pseudomallei, is an important but frequently under-recognised cause of morbidity and mortality in Southeast Asia and elsewhere in the tropics. Data on the epidemiology of paediatric melioidosis in Cambodia are extremely limited. METHODS: Culture-positive melioidosis cases presenting to Angkor Hospital for Children, a non-governmental paediatric hospital located in Siem Reap, Northern Cambodia, between 1st January 2009 and 31st December 2013 were identified by searches of hospital and laboratory databases and logbooks. RESULTS: One hundred seventy-three evaluable cases were identified, presenting from eight provinces. For Siem Reap province, the median commune level incidence was estimated to be 28-35 cases per 100,000 children <15 years per year. Most cases presented during the wet season, May to October. The median age at presentation was 5.7 years (range 8 days-15.9 years). Apart from undernutrition, co-morbidities were rare. Three quarters (131/173) of the children had localised infection, most commonly skin/soft tissue infection (60 cases) or suppurative parotitis (51 cases). There were 39 children with B. pseudomallei bacteraemia: 29 (74.4%) of these had clinical and/or radiological evidence of pneumonia. Overall mortality was 16.8% (29/173) with mortality in bacteraemic cases of 71.8% (28/39). At least seven children did not receive an antimicrobial with activity against B. pseudomallei prior to death. CONCLUSIONS: This retrospective study demonstrated a considerable burden of melioidosis in Cambodian children. Given the high mortality associated with bacteraemic infection, there is an urgent need for greater awareness amongst healthcare professionals in Cambodia and other countries where melioidosis is known or suspected to be endemic. Empiric treatment guidelines should ensure suspected cases are treated early with appropriate antimicrobials.

Wong VK, Baker S, Connor TR, Pickard D, Page AJ, Dave J, Murphy N, Holliman R, Sefton A, Millar M et al. 2016. An extended genotyping framework for Salmonella enterica serovar Typhi, the cause of human typhoid. Nat Commun, 7 pp. 12827. | Show Abstract | Read more

The population of Salmonella enterica serovar Typhi (S. Typhi), the causative agent of typhoid fever, exhibits limited DNA sequence variation, which complicates efforts to rationally discriminate individual isolates. Here we utilize data from whole-genome sequences (WGS) of nearly 2,000 isolates sourced from over 60 countries to generate a robust genotyping scheme that is phylogenetically informative and compatible with a range of assays. These data show that, with the exception of the rapidly disseminating H58 subclade (now designated genotype 4.3.1), the global S. Typhi population is highly structured and includes dozens of subclades that display geographical restriction. The genotyping approach presented here can be used to interrogate local S. Typhi populations and help identify recent introductions of S. Typhi into new or previously endemic locations, providing information on their likely geographical source. This approach can be used to classify clinical isolates and provides a universal framework for further experimental investigations.

Dittrich S, Card E, Phuklia W, Rudgard WE, Silousok J, Phoumin P, Bouthasavong L, Azarian S, Davong V, Dance DAB et al. 2016. Survival and Growth of Orientia tsutsugamushi in Conventional Hemocultures. Emerg Infect Dis, 22 (8), pp. 1460-1463. | Show Abstract | Read more

Orientia tsutsugamushi, which requires specialized facilities for culture, is a substantial cause of disease in Asia. We demonstrate that O. tsutsugamushi numbers increased for up to 5 days in conventional hemocultures. Performing such a culture step before molecular testing could increase the sensitivity of O. tsutsugamushi molecular diagnosis.

Dance DAB. 2016. Challenges in diagnosis and management of melioidosis INTERNATIONAL JOURNAL OF INFECTIOUS DISEASES, 45 pp. 30-30. | Read more

Dittrich S, Rudgard WE, Woods KL, Silisouk J, Phuklia W, Davong V, Vongsouvath M, Phommasone K, Rattanavong S, Knappik M et al. 2016. The Utility of Blood Culture Fluid for the Molecular Diagnosis of Leptospira: A Prospective Evaluation. Am J Trop Med Hyg, 94 (4), pp. 736-740. | Show Abstract | Read more

Leptospirosis is an important zoonosis worldwide, with infections occurring after exposure to contaminated water. Despite being a global problem, laboratory diagnosis remains difficult with culture results taking up to 3 months, serology being retrospective by nature, and polymerase chain reaction showing limited sensitivity. Leptospira have been shown to survive and multiply in blood culture media, and we hypothesized that extracting DNA from incubated blood culture fluid (BCF), followed by quantitative real-time polymerase chain reaction (qPCR) could improve the accuracy and speed of leptospira diagnosis. We assessed this retrospectively, using preincubated BCF of Leptospira spp. positive (N= 109) and negative (N= 63) febrile patients in Vientiane, Lao PDR. The final method showed promising sensitivities of 66% (95% confidence interval [CI]: 55-76) and 59% (95% CI: 49-68) compared with direct or direct and indirect testing combined, as the respective reference standards (specificities > 95%). Despite these promising diagnostic parameters, a subsequent prospective evaluation in a Lao hospital population (N= 352) showed that the sensitivity was very low (∼30%) compared with qPCR on venous blood samples. The disappointingly low sensitivity does suggest that venous blood samples are preferable for the clinical microbiology laboratory, although BCF might be an alternative if leptospirosis is only suspected postadmission after antibiotics have been used.

Rachlin A, Dittrich S, Phommasone K, Douangnouvong A, Phetsouvanh R, Newton PN, Dance DAB. 2016. Investigation of Recurrent Melioidosis in Lao People's Democratic Republic by Multilocus Sequence Typing. Am J Trop Med Hyg, 94 (6), pp. 1208-1211. | Show Abstract | Read more

Melioidosis is an infectious disease caused by the saprophytic bacterium Burkholderia pseudomallei In northeast Thailand and northern Australia, where the disease is highly endemic, a range of molecular tools have been used to study its epidemiology and pathogenesis. In the Lao People's Democratic Republic (Laos) where melioidosis has been recognized as endemic since 1999, no such studies have been undertaken. We used a multilocus sequence typing scheme specific for B. pseudomallei to investigate nine cases of culture-positive recurrence occurring in 514 patients with melioidosis between 2010 and 2015: four were suspected to be relapses while the other five represented reinfections. In addition, two novel sequence types of the bacterium were identified. The low overall recurrence rates (2.4%) and proportions of relapse and reinfection in the Laos are consistent with those described in the recent literature, reflecting the effective use of appropriate antimicrobial therapy.

Beardsley J, Wolbers M, Kibengo FM, Ggayi A-BM, Kamali A, Cuc NTK, Binh TQ, Chau NVV, Farrar J, Merson L et al. 2016. Adjunctive Dexamethasone in HIV-Associated Cryptococcal Meningitis. N Engl J Med, 374 (6), pp. 542-554. | Show Abstract | Read more

BACKGROUND: Cryptococcal meningitis associated with human immunodeficiency virus (HIV) infection causes more than 600,000 deaths each year worldwide. Treatment has changed little in 20 years, and there are no imminent new anticryptococcal agents. The use of adjuvant glucocorticoids reduces mortality among patients with other forms of meningitis in some populations, but their use is untested in patients with cryptococcal meningitis. METHODS: In this double-blind, randomized, placebo-controlled trial, we recruited adult patients with HIV-associated cryptococcal meningitis in Vietnam, Thailand, Indonesia, Laos, Uganda, and Malawi. All the patients received either dexamethasone or placebo for 6 weeks, along with combination antifungal therapy with amphotericin B and fluconazole. RESULTS: The trial was stopped for safety reasons after the enrollment of 451 patients. Mortality was 47% in the dexamethasone group and 41% in the placebo group by 10 weeks (hazard ratio in the dexamethasone group, 1.11; 95% confidence interval [CI], 0.84 to 1.47; P=0.45) and 57% and 49%, respectively, by 6 months (hazard ratio, 1.18; 95% CI, 0.91 to 1.53; P=0.20). The percentage of patients with disability at 10 weeks was higher in the dexamethasone group than in the placebo group, with 13% versus 25% having a prespecified good outcome (odds ratio, 0.42; 95% CI, 0.25 to 0.69; P<0.001). Clinical adverse events were more common in the dexamethasone group than in the placebo group (667 vs. 494 events, P=0.01), with more patients in the dexamethasone group having grade 3 or 4 infection (48 vs. 25 patients, P=0.003), renal events (22 vs. 7, P=0.004), and cardiac events (8 vs. 0, P=0.004). Fungal clearance in cerebrospinal fluid was slower in the dexamethasone group. Results were consistent across Asian and African sites. CONCLUSIONS: Dexamethasone did not reduce mortality among patients with HIV-associated cryptococcal meningitis and was associated with more adverse events and disability than was placebo. (Funded by the United Kingdom Department for International Development and others through the Joint Global Health Trials program; Current Controlled Trials number, ISRCTN59144167.).

Ribolzi O, Rochelle-Newall E, Dittrich S, Auda Y, Newton PN, Rattanavong S, Knappik M, Soulileuth B, Sengtaheuanghoung O, Dance DAB, Pierret A. 2016. Land use and soil type determine the presence of the pathogen Burkholderia pseudomallei in tropical rivers. Environ Sci Pollut Res Int, 23 (8), pp. 7828-7839. | Show Abstract | Read more

Burkholderia pseudomallei is the bacterium that causes melioidosis in humans. While B. pseudomallei is known to be endemic in South East Asia (SEA), the occurrence of the disease in other parts of the tropics points towards a potentially large global distribution. We investigated the environmental factors that influence the presence (and absence) of B. pseudomallei in a tropical watershed in SEA. Our main objective was to determine whether there is a link between the presence of the organism in the hydrographic network and the upstream soil and land-use type. The presence of B. pseudomallei was determined using a specific quantitative real-time PCR assay following enrichment culture. Land use, soil, geomorphology, and environmental data were then analyzed using partial least squares discriminant analysis (PLSDA) to compare the B. pseudomallei positive and negative sites. Soil type in the surrounding catchment and turbidity had a strong positive influence on the presence (acrisols and luvisols) or absence (ferralsols) of B. pseudomallei. Given the strong apparent links between soil characteristics, water turbidity, and the presence/absence of B. pseudomallei, actions to raise public awareness about factors increasing the risk of exposure should be undertaken in order to reduce the incidence of melioidosis in regions of endemicity.

Limmathurotsakul D, Golding N, Dance DA, Messina JP, Pigott DM, Moyes CL, Rolim DB, Bertherat E, Day NP, Peacock SJ, Hay SI. 2016. Predicted global distribution of Burkholderia pseudomallei and burden of melioidosis. Nat Microbiol, 1 (1), | Show Abstract | Read more

Burkholderia pseudomallei, a highly pathogenic bacterium that causes melioidosis, is commonly found in soil in Southeast Asia and Northern Australia1,2. Melioidosis can be difficult to diagnose due to its diverse clinical manifestations and the inadequacy of conventional bacterial identification methods3. The bacterium is intrinsically resistant to a wide range of antimicrobials, and treatment with ineffective antimicrobials may result in case fatality rates (CFRs) exceeding 70%4,5. The importation of infected animals has, in the past, spread melioidosis to non-endemic areas6,7. The global distribution of B. pseudomallei and burden of melioidosis, however, remain poorly understood. Here, we map documented human and animal cases, and the presence of environmental B. pseudomallei, and combine this in a formal modelling framework8-10 to estimate the global burden of melioidosis. We estimate there to be 165,000 (95% credible interval 68,000-412,000) human melioidosis cases per year worldwide, of which 89,000 (36,000-227,000) die. Our estimates suggest that melioidosis is severely underreported in the 45 countries in which it is known to be endemic and that melioidosis is likely endemic in a further 34 countries which have never reported the disease. The large numbers of estimated cases and fatalities emphasise that the disease warrants renewed attention from public health officials and policy makers.

Phommasone K, Althaus T, Souvanthong P, Phakhounthong K, Soyvienvong L, Malapheth P, Mayxay M, Pavlicek RL, Paris DH, Dance D et al. 2016. Accuracy of commercially available c-reactive protein rapid tests in the context of undifferentiated fevers in rural Laos. BMC Infect Dis, 16 (1), pp. 61. | Show Abstract | Read more

BACKGROUND: C-Reactive Protein (CRP) has been shown to be an accurate biomarker for discriminating bacterial from viral infections in febrile patients in Southeast Asia. Here we investigate the accuracy of existing rapid qualitative and semi-quantitative tests as compared with a quantitative reference test to assess their potential for use in remote tropical settings. METHODS: Blood samples were obtained from consecutive patients recruited to a prospective fever study at three sites in rural Laos. At each site, one of three rapid qualitative or semi-quantitative tests was performed, as well as a corresponding quantitative NycoCard Reader II as a reference test. We estimate the sensitivity and specificity of the three tests against a threshold of 10 mg/L and kappa values for the agreement of the two semi-quantitative tests with the results of the reference test. RESULTS: All three tests showed high sensitivity, specificity and kappa values as compared with the NycoCard Reader II. With a threshold of 10 mg/L the sensitivity of the tests ranged from 87-98 % and the specificity from 91-98 %. The weighted kappa values for the semi-quantitative tests were 0.7 and 0.8. CONCLUSION: The use of CRP rapid tests could offer an inexpensive and effective approach to improve the targeting of antibiotics in remote settings where health facilities are basic and laboratories are absent. This study demonstrates that accurate CRP rapid tests are commercially available; evaluations of their clinical impact and cost-effectiveness at point of care is warranted.

Rattanavong S, Dance DAB, Davong V, Baker C, Frost H, Phetsouvanh R, Vongsouvath M, Newton PN, Steer AC, Smeesters PR. 2016. Group A streptococcal strains isolated in Lao People's Democratic Republic from 2004 to 2013. Epidemiol Infect, 144 (8), pp. 1770-1773. | Show Abstract | Read more

Epidemiological data regarding group A streptococcal (GAS) infections in South East Asia are scarce with no information from Laos. We characterized emm types, emm clusters and the antibiotic resistance profile of 124 GAS isolates recovered in Laos during 2004-2013. Most strains were recovered from skin and invasive infections (76% and 19%, respectively). Thirty-four emm types were identified as belonging to 12 emm clusters and no novel emm types were identified. No significant differences were observed in the distribution of emm types or emm clusters according to age or site of recovery (skin or invasive infections). There was moderate strain diversity in this country but considerable differences in emm-type distribution between Laos, Thailand and Cambodia. Vaccine coverage was high for the J8 vaccine candidate. The theoretical coverage for the 30-valent vaccine candidate needs further investigation. Antibiotic resistance was moderate to erythromycin and chloramphenicol (8% and 7%, respectively) and low to ofloxacin (<1%).

Tauran PM, Sennang N, Rusli B, Wiersinga WJ, Dance D, Arif M, Limmathurotsakul D. 2015. Emergence of Melioidosis in Indonesia. Am J Trop Med Hyg, 93 (6), pp. 1160-1163. | Show Abstract | Read more

Melioidosis is known to be highly endemic in parts of southeast Asia and northern Australia; however, cases are rarely reported in Indonesia. Here we report three cases of melioidosis in Makassar, South Sulawesi, Indonesia occurring between 2013 and 2014. Two patients died and the other was lost to follow-up. Burkholderia pseudomallei isolates from all three cases were identified by the VITEK2 Compact installed in the hospital in 2012. None of the three patients reported received antimicrobials recommended for melioidosis because of the delayed recognition of the organism. We reviewed the literature and found only seven reports of melioidosis in Indonesia. Five were reported before 1960. We suggest that melioidosis is endemic throughout Indonesia but currently under-recognized. Training on how to identify B. pseudomallei accurately and safely in all available microbiological facilities should be provided, and consideration should be given to making melioidosis a notifiable disease in Indonesia.

Parry CM, Thieu NTV, Dolecek C, Karkey A, Gupta R, Turner P, Dance D, Maude RR, Ha V, Tran CN et al. 2015. Erratum for Parry et al., Clinically and microbiologically derived azithromycin susceptibility breakpoints for Salmonella enterica serovars Typhi and Paratyphi A. Antimicrob Agents Chemother, 59 (7), pp. 4364. | Read more

Holt KE, Wertheim H, Zadoks RN, Baker S, Whitehouse CA, Dance D, Jenney A, Connor TR, Hsu LY, Severin J et al. 2015. Genomic analysis of diversity, population structure, virulence, and antimicrobial resistance in Klebsiella pneumoniae, an urgent threat to public health. Proc Natl Acad Sci U S A, 112 (27), pp. E3574-E3581. | Show Abstract | Read more

Klebsiella pneumoniae is now recognized as an urgent threat to human health because of the emergence of multidrug-resistant strains associated with hospital outbreaks and hypervirulent strains associated with severe community-acquired infections. K. pneumoniae is ubiquitous in the environment and can colonize and infect both plants and animals. However, little is known about the population structure of K. pneumoniae, so it is difficult to recognize or understand the emergence of clinically important clones within this highly genetically diverse species. Here we present a detailed genomic framework for K. pneumoniae based on whole-genome sequencing of more than 300 human and animal isolates spanning four continents. Our data provide genome-wide support for the splitting of K. pneumoniae into three distinct species, KpI (K. pneumoniae), KpII (K. quasipneumoniae), and KpIII (K. variicola). Further, for K. pneumoniae (KpI), the entity most frequently associated with human infection, we show the existence of >150 deeply branching lineages including numerous multidrug-resistant or hypervirulent clones. We show K. pneumoniae has a large accessory genome approaching 30,000 protein-coding genes, including a number of virulence functions that are significantly associated with invasive community-acquired disease in humans. In our dataset, antimicrobial resistance genes were common among human carriage isolates and hospital-acquired infections, which generally lacked the genes associated with invasive disease. The convergence of virulence and resistance genes potentially could lead to the emergence of untreatable invasive K. pneumoniae infections; our data provide the whole-genome framework against which to track the emergence of such threats.

Nasner-Posso KM, Cruz-Calderón S, Montúfar-Andrade FE, Dance DAB, Rodriguez-Morales AJ. 2015. Human melioidosis reported by ProMED. Int J Infect Dis, 35 pp. 103-106. | Show Abstract | Read more

OBJECTIVE: There are limited sources describing the global burden of emerging diseases. A review of human melioidosis reported by ProMED was performed and the reliability of the data retrieved assessed in comparison to published reports. The effectiveness of ProMED was evaluated as a source of epidemiological data by focusing on melioidosis. METHODS: Using the keyword 'melioidosis' in the ProMED search engine, all of the information from the reports and collected data was reviewed using a structured form, including the year, country, gender, occupation, number of infected individuals, and number of fatal cases. RESULTS: One hundred and twenty-four entries reported between January 1995 and October 2014 were identified. A total of 4630 cases were reported, with death reported in 505 cases, suggesting a misleadingly low overall case fatality rate (CFR) of 11%. Of 20 cases for which the gender was reported, 12 (60%) were male. Most of the cases were reported from Australia, Thailand, Singapore, Vietnam, and Malaysia, with sporadic reports from other countries. CONCLUSIONS: Internet-based reporting systems such as ProMED are useful to gather information and synthesize knowledge on emerging infections. Although certain areas need to be improved, ProMED provided good information about melioidosis.

Vongphoumy I, Dance DAB, Dittrich S, Logan J, Davong V, Rattanavong S, Blessmann J. 2015. Case report: Actinomycetoma caused by Nocardia aobensis from Lao PDR with favourable outcome after short-term antibiotic treatment. PLoS Negl Trop Dis, 9 (4), pp. e0003729. | Show Abstract | Read more

BACKGROUND: Mycetoma is a neglected, chronic, localized, progressively destructive, granulomatous infection caused either by fungi (eumycetoma) or by aerobic actinomycetes (actinomycetoma). It is characterized by a triad of painless subcutaneous mass, multiple sinuses and discharge containing grains. Mycetoma commonly affects young men aged between 20 and 40 years with low socioeconomic status, particularly farmers and herdsmen. METHODOLOGY/PRINCIPAL FINDINGS: A 30 year-old male farmer from an ethnic minority in Phin District, Savannakhet Province, Lao PDR (Laos) developed a painless swelling with multiple draining sinuses of his right foot over a period of approximately 3 years. X-ray of the right foot showed osteolysis of tarsals and metatarsals. Aerobic culture of sinus discharge yielded large numbers of Staphylococcus aureus and a slow growing Gram-positive rod. The organism was subsequently identified as Nocardia aobensis by 16S ribosomal RNA gene sequencing. The patient received antimicrobial treatment with amikacin and trimethoprim-sulfamethoxazole according to consensus treatment guidelines. Although slight improvement was noted the patient left the hospital after 14 days and did not take any more antibiotics. Over the following 22 weeks the swelling of his foot subsequently diminished together with healing of discharging sinuses. CONCLUSION: This is the first published case of Actinomycetoma caused by Nocardia aobensis and the second case of Actinomycetoma from Laos. A treatment course of only 14 days with amikacin and trimethoprim-sulfamethoxazole was apparently sufficient to cure the infection, although long-term treatment up to one year is currently recommended. Treatment trials or prospective descriptions of outcome for actinomycetoma should investigate treatment efficacy for the different members of Actinomycetales, particularly Nocardia spp., with short-term and long-term treatment courses.

Knappik M, Dance DAB, Rattanavong S, Pierret A, Ribolzi O, Davong V, Silisouk J, Vongsouvath M, Newton PN, Dittrich S. 2015. Evaluation of Molecular Methods To Improve the Detection of Burkholderia pseudomallei in Soil and Water Samples from Laos. Appl Environ Microbiol, 81 (11), pp. 3722-3727. | Show Abstract | Read more

Burkholderia pseudomallei is the cause of melioidosis, a severe and potentially fatal disease of humans and animals. It is endemic in northern Australia and Southeast Asia and is found in soil and surface water. The environmental distribution of B. pseudomallei worldwide and within countries where it is endemic, such as the Lao People's Democratic Republic (Laos), remains unclear. However, this knowledge is important to our understanding of the ecology and epidemiology of B. pseudomallei and to facilitate public health interventions. Sensitive and specific methods to detect B. pseudomallei in environmental samples are therefore needed. The aim of this study was to compare molecular and culture-based methods for the detection of B. pseudomallei in soil and surface water in order to identify the optimal approach for future environmental studies in Laos. Molecular detection by quantitative real-time PCR (qPCR) was attempted after DNA extraction directly from soil or water samples or after an overnight enrichment step. The positivity rates obtained by qPCR were compared to those obtained by different culture techniques. The rate of detection from soil samples by qPCR following culture enrichment was significantly higher (84/100) than that by individual culture methods and all culture methods combined (44/100; P < 0.001). Similarly, qPCR following enrichment was the most sensitive method for filtered river water compared with the sensitivity of the individual methods and all individual methods combined. In conclusion, molecular detection following an enrichment step has proven to be a sensitive and reliable approach for B. pseudomallei detection in Lao environmental samples and is recommended as the preferred method for future surveys.

Nic Fhogartaigh C, Dance DAB, Davong V, Tann P, Phetsouvanh R, Turner P, Dittrich S, Newton PN. 2015. A novel technique for detecting antibiotic-resistant typhoid from rapid diagnostic tests. J Clin Microbiol, 53 (5), pp. 1758-1760. | Show Abstract | Read more

Fluoroquinolone-resistant typhoid is increasing. An antigen-detecting rapid diagnostic test (RDT) can rapidly diagnose typhoid from blood cultures. A simple, inexpensive molecular technique performed with DNA from positive RDTs accurately identified gyrA mutations consistent with phenotypic susceptibility testing results. Field diagnosis combined with centralized molecular resistance testing could improve typhoid management and surveillance in low-resource settings.

Parry CM, Thieu NTV, Dolecek C, Karkey A, Gupta R, Turner P, Dance D, Maude RR, Ha V, Tran CN et al. 2015. Clinically and microbiologically derived azithromycin susceptibility breakpoints for Salmonella enterica serovars Typhi and Paratyphi A. Antimicrob Agents Chemother, 59 (5), pp. 2756-2764. | Show Abstract | Read more

Azithromycin is an effective treatment for uncomplicated infections with Salmonella enterica serovar Typhi and serovar Paratyphi A (enteric fever), but there are no clinically validated MIC and disk zone size interpretative guidelines. We studied individual patient data from three randomized controlled trials (RCTs) of antimicrobial treatment in enteric fever in Vietnam, with azithromycin used in one treatment arm, to determine the relationship between azithromycin treatment response and the azithromycin MIC of the infecting isolate. We additionally compared the azithromycin MIC and the disk susceptibility zone sizes of 1,640 S. Typhi and S. Paratyphi A clinical isolates collected from seven Asian countries. In the RCTs, 214 patients who were treated with azithromycin at a dose of 10 to 20 mg/ml for 5 to 7 days were analyzed. Treatment was successful in 195 of 214 (91%) patients, with no significant difference in response (cure rate, fever clearance time) with MICs ranging from 4 to 16 μg/ml. The proportion of Asian enteric fever isolates with an MIC of ≤ 16 μg/ml was 1,452/1,460 (99.5%; 95% confidence interval [CI], 98.9 to 99.7) for S. Typhi and 207/240 (86.3%; 95% CI, 81.2 to 90.3) (P < 0.001) for S. Paratyphi A. A zone size of ≥ 13 mm to a 5-μg azithromycin disk identified S. Typhi isolates with an MIC of ≤ 16 μg/ml with a sensitivity of 99.7%. An azithromycin MIC of ≤ 16 μg/ml or disk inhibition zone size of ≥ 13 mm enabled the detection of susceptible S. Typhi isolates that respond to azithromycin treatment. Further work is needed to define the response to treatment in S. Typhi isolates with an azithromycin MIC of >16 μg/ml and to determine MIC and disk breakpoints for S. Paratyphi A.

Stoesser N, Xayaheuang S, Vongsouvath M, Phommasone K, Elliott I, Del Ojo Elias C, Crook DW, Newton PN, Buisson Y, Lee SJ, Dance DAB. 2015. Colonization with Enterobacteriaceae producing ESBLs in children attending pre-school childcare facilities in the Lao People's Democratic Republic. J Antimicrob Chemother, 70 (6), pp. 1893-1897. | Show Abstract | Read more

OBJECTIVES: Intestinal carriage constitutes an important reservoir of antimicrobial-resistant bacteria, with some of the highest rates reported from Asia. Antibiotic resistance has been little studied in Laos, where some antibiotics are available without restriction, but others such as carbapenems are not available. PATIENTS AND METHODS: We collected stools from 397 healthy children in 12 randomly selected pre-school childcare facilities in and around Vientiane. Colonization with ESBL-producing Enterobacteriaceae (ESBLE) and carbapenemase-producing Enterobacteriaceae (CPE) was detected using a disc diffusion screening test and ESBLE were characterized using WGS. Risk factor data were collected by questionnaire. RESULTS: Ninety-two children (23%) were colonized with ESBLE, mainly Escherichia coli carrying blaCTX-M and Klebsiella pneumoniae carrying blaSHV or blaCTX-M, which were frequently resistant to multiple antibiotic classes. Although residence in Vientiane Capital, foreign travel, higher maternal level of education, antibiotic use in the preceding 3 months and attending a childcare facility with a 'good' level of hygiene were all associated with ESBLE colonization on univariable analysis, a significant association remained only for antibiotic use when a stepwise approach was used with a multivariate random-effects model. WGS analysis suggested transmission in both childcare facilities and community settings. CONCLUSIONS: The high prevalence of paediatric colonization with ESBLE in Laos, one of the highest reported in Asia, is probably the result of inappropriate antibiotic use. Paediatric colonization with CPE was not identified in this study, but it is important to continue to monitor the spread of antibiotic-resistant Enterobacteriaceae in Laos.

Dittrich S, Rattanavong S, Lee SJ, Panyanivong P, Craig SB, Tulsiani SM, Blacksell SD, Dance DAB, Dubot-Pérès A, Sengduangphachanh A et al. 2015. Orientia, rickettsia, and leptospira pathogens as causes of CNS infections in Laos: a prospective study. Lancet Glob Health, 3 (2), pp. e104-e112. | Show Abstract | Read more

BACKGROUND: Scrub typhus (caused by Orientia tsutsugamushi), murine typhus (caused by Rickettsia typhi), and leptospirosis are common causes of febrile illness in Asia; meningitis and meningoencephalitis are severe complications. However, scarce data exist for the burden of these pathogens in patients with CNS disease in endemic countries. Laos is representative of vast economically poor rural areas in Asia with little medical information to guide public health policy. We assessed whether these pathogens are important causes of CNS infections in Laos. METHODS: Between Jan 10, 2003, and Nov 25, 2011, we enrolled 1112 consecutive patients of all ages admitted with CNS symptoms or signs requiring a lumbar puncture at Mahosot Hospital, Vientiane, Laos. Microbiological examinations (culture, PCR, and serology) targeted so-called conventional bacterial infections (Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, S suis) and O tsutsugamushi, Rickettsia typhi/Rickettsia spp, and Leptospira spp infections in blood or cerebrospinal fluid (CSF). We analysed and compared causes and clinical and CSF characteristics between patient groups. FINDINGS: 1051 (95%) of 1112 patients who presented had CSF available for analysis, of whom 254 (24%) had a CNS infection attributable to a bacterial or fungal pathogen. 90 (35%) of these 254 infections were caused by O tsutsugamushi, R typhi/Rickettsia spp, or Leptospira spp. These pathogens were significantly more frequent than conventional bacterial infections (90/1051 [9%] vs 42/1051 [4%]; p<0·0001) by use of conservative diagnostic definitions. CNS infections had a high mortality (236/876 [27%]), with 18% (13/71) for R typhi/Rickettsia spp, O tsutsugamushi, and Leptospira spp combined, and 33% (13/39) for conventional bacterial infections (p=0·076). INTERPRETATION: Our data suggest that R typhi/Rickettsia spp, O tsutsugamushi, and Leptospira spp infections are important causes of CNS infections in Laos. Antibiotics, such as tetracyclines, needed for the treatment of murine typhus and scrub typhus, are not routinely advised for empirical treatment of CNS infections. These severely neglected infections represent a potentially large proportion of treatable CNS disease burden across vast endemic areas and need more attention. FUNDING: Wellcome Trust UK.

Wong VK, Baker S, Pickard DJ, Parkhill J, Page AJ, Feasey NA, Kingsley RA, Thomson NR, Keane JA, Weill F-X et al. 2015. Phylogeographical analysis of the dominant multidrug-resistant H58 clade of Salmonella Typhi identifies inter- and intracontinental transmission events. Nat Genet, 47 (6), pp. 632-639. | Show Abstract | Read more

The emergence of multidrug-resistant (MDR) typhoid is a major global health threat affecting many countries where the disease is endemic. Here whole-genome sequence analysis of 1,832 Salmonella enterica serovar Typhi (S. Typhi) identifies a single dominant MDR lineage, H58, that has emerged and spread throughout Asia and Africa over the last 30 years. Our analysis identifies numerous transmissions of H58, including multiple transfers from Asia to Africa and an ongoing, unrecognized MDR epidemic within Africa itself. Notably, our analysis indicates that H58 lineages are displacing antibiotic-sensitive isolates, transforming the global population structure of this pathogen. H58 isolates can harbor a complex MDR element residing either on transmissible IncHI1 plasmids or within multiple chromosomal integration sites. We also identify new mutations that define the H58 lineage. This phylogeographical analysis provides a framework to facilitate global management of MDR typhoid and is applicable to similar MDR lineages emerging in other bacterial species.

Hoffmaster AR, AuCoin D, Baccam P, Baggett HC, Baird R, Bhengsri S, Blaney DD, Brett PJ, Brooks TJG, Brown KA et al. 2015. Melioidosis diagnostic workshop, 2013. Emerg Infect Dis, 21 (2), pp. 1-9. | Show Abstract | Read more

Melioidosis is a severe disease that can be difficult to diagnose because of its diverse clinical manifestations and a lack of adequate diagnostic capabilities for suspected cases. There is broad interest in improving detection and diagnosis of this disease not only in melioidosis-endemic regions but also outside these regions because melioidosis may be underreported and poses a potential bioterrorism challenge for public health authorities. Therefore, a workshop of academic, government, and private sector personnel from around the world was convened to discuss the current state of melioidosis diagnostics, diagnostic needs, and future directions.

Mirabel M, Rattanavong S, Frichitthavong K, Chu V, Kesone P, Thongsith P, Jouven X, Fournier P-E, Dance DAB, Newton PN. 2015. Infective endocarditis in the Lao PDR: clinical characteristics and outcomes in a developing country. Int J Cardiol, 180 pp. 270-273. | Show Abstract | Read more

INTRODUCTION: Data on infective endocarditis (IE) in Southeast Asia are scarce. OBJECTIVES: To describe the clinical epidemiology of IE in Lao PDR, a lower middle-income country. METHODS: A single centre retrospective study at Mahosot Hospital, Vientiane. Patients aged over 1year of age admitted 2006-2012 to Mahosot Hospital with definite or possible IE by modified Duke criteria were included. RESULTS: Thirty-six patients fulfilled the inclusion criteria; 33 (91.7%) had left-sided IE. Eleven (30.6%) had definite IE and 25 (69.4%) possible left-sided IE. Median age was 25years old [IQR 18-42]. Fifteen patients (41.7%) were males. Underlying heart diseases included: rheumatic valve disease in 12 (33.3%), congenital heart disease in 7 (19.4%), degenerative valve disease in 3 (8.3%), and of unknown origin in 14 (38.9%) patients. Native valve IE was present in 30 patients (83.3%), and prosthetic valve IE in 6 patients (16.7%). The most frequent pathogens were Streptococcus spp. in 7 (19.4%). Blood cultures were negative in 22 patients (61.1%). Complications included: heart failure in 11 (30.6%), severe valve regurgitation in 7 (19.4%); neurological event in 7 (19.4%); septic shock or severe sepsis in 5 (13.9%); and cardiogenic shock in 3 patients (8.3%). No patient underwent heart surgery. Fourteen (38.9%) had died by follow-up after a median of 2.1years [IQR 1-3.2]; and 3 (8.3%) were lost to follow-up. CONCLUSIONS: Infective endocarditis, a disease especially of young adults and mainly caused by Streptococcus spp., was associated with rheumatic heart disease and had high mortality in Laos.

Day J, Imran D, Ganiem AR, Tjahjani N, Wahyuningsih R, Adawiyah R, Dance D, Mayxay M, Newton P, Phetsouvanh R et al. 2014. CryptoDex: a randomised, double-blind, placebo-controlled phase III trial of adjunctive dexamethasone in HIV-infected adults with cryptococcal meningitis: study protocol for a randomised control trial. Trials, 15 (1), pp. 441. | Show Abstract | Read more

BACKGROUND: Cryptococcal meningitis (CM) is a severe AIDS-defining illness with 90-day case mortality as high as 70% in sub-Saharan Africa, despite treatment. It is the leading cause of death in HIV patients in Asia and Africa.No major advance has been made in the treatment of CM since the 1970s. The mainstays of induction therapy are amphotericin B and flucytosine, but these are often poorly available where the disease burden is highest. Adjunctive treatments, such as dexamethasone, have had dramatic effects on mortality in other neurologic infections, but are untested in CM. Given the high death rates in patients receiving current optimal treatment, and the lack of new agents on the horizon, adjuvant treatments, which offer the potential to reduce mortality in CM, should be tested.The principal research question posed by this study is as follows: does adding dexamethasone to standard antifungal therapy for CM reduce mortality? Dexamethasone is a cheap, readily available, and practicable intervention. METHOD: A double-blind placebo-controlled trial with parallel arms in which patients are randomised to receive either dexamethasone or placebo, in addition to local standard of care. The study recruits patients in both Asia and Africa to ensure the relevance of its results to the populations in which the disease burden is highest. The 10-week mortality risk in the control group is expected to be between 30% and 50%, depending on location, and the target hazard ratio of 0.7 corresponds to absolute risk reductions in mortality from 30% to 22%, or from 50% to 38%. Assuming an overall 10-week mortality of at least 30% in our study population, recruitment of 824 patients will be sufficient to observe the expected number of deaths. Allowing for some loss to follow-up, the total sample size for this study is 880 patients. To generate robust evidence across both continents, we aim to recruit roughly similar numbers of patients from each continent. The primary end point is 10-week mortality. Ethical approval has been obtained from Oxford University's Tropical Research Ethics Committee (OxTREC), and as locally mandated at each site. TRIAL REGISTRATION: International Standard Randomised Controlled Trial Number: ISRCTN59144167 26-July-2012.

Dance DAB. 2015. Editorial commentary: melioidosis in Puerto Rico: the iceberg slowly emerges. Clin Infect Dis, 60 (2), pp. 251-253. | Read more

Dance DAB, Davong V, Soeng S, Phetsouvanh R, Newton PN, Turner P. 2014. Trimethoprim/sulfamethoxazole resistance in Burkholderia pseudomallei. Int J Antimicrob Agents, 44 (4), pp. 368-369. | Read more

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Dance D. 2014. Treatment and prophylaxis of melioidosis International Journal of Antimicrobial Agents, 43 (4), pp. 310-318. | Show Abstract | Read more

Melioidosis, infection with Burkholderia pseudomallei, is being recognised with increasing frequency and is probably more common than currently appreciated. Treatment recommendations are based on a series of clinical trials conducted in Thailand over the past 25 years. Treatment is usually divided into two phases: in the first, or acute phase, parenteral drugs are given for =10 days with the aim of preventing death from overwhelming sepsis; in the second, or eradication phase, oral drugs are given, usually to complete a total of 20 weeks, with the aim of preventing relapse. Specific treatment for individual patients needs to be tailored according to clinical manifestations and response, and there remain many unanswered questions. Some patients with very mild infections can probably be cured by oral agents alone. Ceftazidime is the mainstay of acute-phase treatment, with carbapenems reserved for severe infections or treatment failures and amoxicillin/clavulanic acid (co-amoxiclav) as second-line therapy. Trimethoprim/sulfamethoxazole (co-trimoxazole) is preferred for the eradication phase, with the alternative of co-amoxiclav. In addition, the best available supportive care is needed, along with drainage of abscesses whenever possible. Treatment for melioidosis is unaffordable for many in endemic areas of the developing world, but the relative costs have reduced over the past decade. Unfortunately there is no likelihood of any new or cheaper options becoming available in the immediate future. Recommendations for prophylaxis following exposure to B. pseudomallei have been made, but the evidence suggests that they would probably only delay rather than prevent the development of infection. © 2014 The Author.

Dance D. 2014. Treatment and prophylaxis of melioidosis. Int J Antimicrob Agents, 43 (4), pp. 310-318. | Show Abstract | Read more

Melioidosis, infection with Burkholderia pseudomallei, is being recognised with increasing frequency and is probably more common than currently appreciated. Treatment recommendations are based on a series of clinical trials conducted in Thailand over the past 25 years. Treatment is usually divided into two phases: in the first, or acute phase, parenteral drugs are given for ≥10 days with the aim of preventing death from overwhelming sepsis; in the second, or eradication phase, oral drugs are given, usually to complete a total of 20 weeks, with the aim of preventing relapse. Specific treatment for individual patients needs to be tailored according to clinical manifestations and response, and there remain many unanswered questions. Some patients with very mild infections can probably be cured by oral agents alone. Ceftazidime is the mainstay of acute-phase treatment, with carbapenems reserved for severe infections or treatment failures and amoxicillin/clavulanic acid (co-amoxiclav) as second-line therapy. Trimethoprim/sulfamethoxazole (co-trimoxazole) is preferred for the eradication phase, with the alternative of co-amoxiclav. In addition, the best available supportive care is needed, along with drainage of abscesses whenever possible. Treatment for melioidosis is unaffordable for many in endemic areas of the developing world, but the relative costs have reduced over the past decade. Unfortunately there is no likelihood of any new or cheaper options becoming available in the immediate future. Recommendations for prophylaxis following exposure to B. pseudomallei have been made, but the evidence suggests that they would probably only delay rather than prevent the development of infection.

Nic Fhogartaigh C, Dance DAB. 2013. Bacterial gastroenteritis Medicine, 41 (12), pp. 693-699. | Show Abstract | Read more

Infectious diarrhoea is a major public health concern worldwide. Bacteria, the focus of this review, are responsible for 20-40% of diarrhoeal episodes, contributing to high rates of childhood mortality in developing regions, and substantial morbidity and economic losses in developed regions. The epidemiology is changing with salmonellosis decreasing in industrialized countries and diarrhoeagenic Escherichia coli contributing to an increasing burden of disease worldwide. Molecular diagnostics have improved our understanding of the epidemiology, aetiology and pathogenesis of bacterial gastroenteritis, and have revealed new pathogenic agents, although widespread introduction of such diagnostics into clinical practice will require careful cost-benefit analyses. The development of antimicrobial resistance in gastrointestinal pathogens has implications for treatment options. We review the epidemiology of infectious diarrhoea, the principal aetiological agents and their clinical features, and the diagnosis, treatment and prevention of bacterial gastroenteritis; we also propose an investigation and management algorithm. © 2013 Elsevier Ltd. All rights reserved.

Goodyear A, Strange L, Rholl DA, Silisouk J, Dance DAB, Schweizer HP, Dow S. 2013. An improved selective culture medium enhances the isolation of Burkholderia pseudomallei from contaminated specimens. Am J Trop Med Hyg, 89 (5), pp. 973-982. | Show Abstract | Read more

Burkholderia pseudomallei is a Gram-negative environmental bacterium found in tropical climates that causes melioidosis. Culture remains the diagnostic gold standard, but isolation of B. pseudomallei from heavily contaminated sites, such as fecal specimens, can be difficult. We recently reported that B. pseudomallei is capable of infecting the gastrointestinal tract of mice and suggested that the same may be true in humans. Thus, there is a strong need for new culture techniques to allow for efficient detection of B. pseudomallei in fecal and other specimens. We found that the addition of norfloxacin, ampicillin, and polymyxin B to Ashdown's medium (NAP-A) resulted in increased specificity without affecting the growth of 25 B. pseudomallei strains. Furthermore, recovery of B. pseudomallei from human clinical specimens was not affected by the three additional antibiotics. Therefore, we conclude that NAP-A medium provides a new tool for more sensitive isolation of B. pseudomallei from heavily contaminated sites.

Anderson M, Luangxay K, Sisouk K, Vorlasan L, Soumphonphakdy B, Sengmouang V, Chansamouth V, Phommasone K, Van Dyke R, Chong E et al. 2014. Epidemiology of bacteremia in young hospitalized infants in Vientiane, Laos, 2000-2011. J Trop Pediatr, 60 (1), pp. 10-16. | Show Abstract | Read more

As data about the causes of neonatal sepsis in low-income countries are inadequate, we reviewed the etiology and antibiotic susceptibilities of bacteremia in young infants in Laos. As Staphylococcus aureus is the leading cause of bacteremia in Lao infants, we also examined risk factors for this infection, in particular the local practice of warming mothers during the first weeks postpartum with hot coals under their beds (hot beds). Clinical and laboratory data regarding infants aged 0-60 days evaluated for sepsis within 72 h of admission to Mahosot Hospital in Vientiane, Laos, were reviewed, and 85 of 1438 (5.9%) infants' blood cultures grew a clinically significant organism. Most common were S. aureus, Escherichia coli and Klebsiella pneumoniae. Whereas no methicillin-resistant S. aureus was found, only 18% of E. coli isolates were susceptible to ampicillin. A history of sleeping on a hot bed with mother was associated with S. aureus bacteremia (odds ratio 4.8; 95% confidence interval 1.2-19.0).

Katangwe T, Purcell J, Bar-Zeev N, Denis B, Montgomery J, Alaerts M, Heyderman RS, Dance DAB, Kennedy N, Feasey N, Moxon CA. 2013. Human melioidosis, Malawi, 2011. Emerg Infect Dis, 19 (6), pp. 981-984. | Show Abstract | Read more

A case of human melioidosis caused by a novel sequence type of Burkholderia pseudomallei occurred in a child in Malawi, southern Africa. A literature review showed that human cases reported from the continent have been increasing.

Limmathurotsakul D, Dance DAB, Wuthiekanun V, Kaestli M, Mayo M, Warner J, Wagner DM, Tuanyok A, Wertheim H, Yoke Cheng T et al. 2013. Systematic review and consensus guidelines for environmental sampling of Burkholderia pseudomallei. PLoS Negl Trop Dis, 7 (3), pp. e2105. | Show Abstract | Read more

BACKGROUND: Burkholderia pseudomallei, a Tier 1 Select Agent and the cause of melioidosis, is a Gram-negative bacillus present in the environment in many tropical countries. Defining the global pattern of B. pseudomallei distribution underpins efforts to prevent infection, and is dependent upon robust environmental sampling methodology. Our objective was to review the literature on the detection of environmental B. pseudomallei, update the risk map for melioidosis, and propose international consensus guidelines for soil sampling. METHODS/PRINCIPAL FINDINGS: An international working party (Detection of Environmental Burkholderia pseudomallei Working Party (DEBWorP)) was formed during the VIth World Melioidosis Congress in 2010. PubMed (January 1912 to December 2011) was searched using the following MeSH terms: pseudomallei or melioidosis. Bibliographies were hand-searched for secondary references. The reported geographical distribution of B. pseudomallei in the environment was mapped and categorized as definite, probable, or possible. The methodology used for detecting environmental B. pseudomallei was extracted and collated. We found that global coverage was patchy, with a lack of studies in many areas where melioidosis is suspected to occur. The sampling strategies and bacterial identification methods used were highly variable, and not all were robust. We developed consensus guidelines with the goals of reducing the probability of false-negative results, and the provision of affordable and 'low-tech' methodology that is applicable in both developed and developing countries. CONCLUSIONS/SIGNIFICANCE: The proposed consensus guidelines provide the basis for the development of an accurate and comprehensive global map of environmental B. pseudomallei.

Cheng AC, Currie BJ, Dance DAB, Funnell SGP, Limmathurotsakul D, Simpson AJH, Peacock SJ. 2013. Clinical definitions of melioidosis. Am J Trop Med Hyg, 88 (3), pp. 411-413. | Show Abstract | Read more

Clinical definitions of melioidosis and inhalation-acquired melioidosis (Burkholderia pseudomallei infection) are described together with the evidence used to develop these definitions. Such definitions support accurate public health reporting, preparedness planning for deliberate B. pseudomallei release, design of experimental models, and categorization of naturally acquired melioidosis.

Lipsitz R, Garges S, Aurigemma R, Baccam P, Blaney DD, Cheng AC, Currie BJ, Dance D, Gee JE, Larsen J et al. 2012. Workshop on treatment of and postexposure prophylaxis for Burkholderia pseudomallei and B. mallei Infection, 2010. Emerg Infect Dis, 18 (12), pp. e2. | Show Abstract | Read more

The US Public Health Emergency Medical Countermeasures Enterprise convened subject matter experts at the 2010 HHS Burkholderia Workshop to develop consensus recommendations for postexposure prophylaxis against and treatment for Burkholderia pseudomallei and B. mallei infections, which cause melioidosis and glanders, respectively. Drugs recommended by consensus of the participants are ceftazidime or meropenem for initial intensive therapy, and trimethoprim/sulfamethoxazole or amoxicillin/clavulanic acid for eradication therapy. For postexposure prophylaxis, recommended drugs are trimethoprim/sulfamethoxazole or co-amoxiclav. To improve the timely diagnosis of melioidosis and glanders, further development and wide distribution of rapid diagnostic assays were also recommended. Standardized animal models and B. pseudomallei strains are needed for further development of therapeutic options. Training for laboratory technicians and physicians would facilitate better diagnosis and treatment options.

Castonguay-Vanier J, Davong V, Bouthasavong L, Sengdetka D, Simmalavong M, Seupsavith A, Dance DAB, Baker S, Le Thi Phuong T, Vongsouvath M, Newton PN. 2013. Evaluation of a simple blood culture amplification and antigen detection method for diagnosis of Salmonella enterica serovar typhi bacteremia. J Clin Microbiol, 51 (1), pp. 142-148. | Show Abstract | Read more

In most areas where typhoid is endemic, laboratory diagnosis is not possible due to the lack of appropriate facilities. We investigated whether the combination of blood culture amplification of Salmonella enterica serovar Typhi with an S. Typhi antigen rapid diagnostic test (RDT) could be an accurate and inexpensive tool for the accelerated diagnosis of patients with acute typhoid in Laos. For a panel of 23 Gram-negative reference pathogens, the Standard Diagnostics (catalog no. 15FK20; Kyonggi-do, South Korea) RDT gave positive results for S. Typhi NCTC 8385, S. Typhi NCTC 786 (Vi negative), Salmonella enterica serovar Enteritidis (ATCC 13076), and Salmonella enterica serovar Ndolo NCTC 8700 (all group D). In a prospective study of 6,456 blood culture bottles from 3,028 patients over 15 months, 392 blood culture bottles (6.1%) from 221 (7.3%) patients had Gram-negative rods (GNRs) seen in the blood culture fluid. The sensitivity, negative predictive value, specificity, and positive predictive value were 96.7%, 99.5%, 97.9%, and 87.9%, respectively, for patients with proven S. Typhi bacteremia and 91.2%, 98.4%, 98.9%, and 93.9% for patients with group D Salmonella. The median (range) number of days between diagnosis by RDT and reference assays was 1 (-1 to +2) day for those with confirmed S. Typhi. The use of antigen-based pathogen detection in blood culture fluid may be a useful, relatively rapid, inexpensive, and accurate technique for the identification of important causes of bacteremia in the tropics.

Wootton CI, Elliott IAM, Sengdetkha D, Vongsouvath M, Phongmany S, Dance DAB. 2013. Melioidosis: an unusual cause of recurrent buttock abscesses. Clin Exp Dermatol, 38 (4), pp. 427-428. | Read more

Rattanavong S, Vongthongchit S, Bounphamala K, Vongphakdy P, Gubler J, Mayxay M, Phetsouvanh R, Elliott I, Logan J, Hill R et al. 2012. Actinomycetoma in SE Asia: the first case from Laos and a review of the literature. BMC Infect Dis, 12 (1), pp. 349. | Show Abstract | Read more

BACKGROUND: Mycetoma is a chronic, localized, slowly progressing infection of the cutaneous and subcutaneous tissues caused either by fungi (eumycetoma or implantation mycosis) or by aerobic actinomycetes (actinomycetoma). It is acquired by traumatic implantation, most commonly in the tropics and subtropics, especially in rural agricultural communities. Although well recognized elsewhere in Asia, it has not been reported from the Lao People's Democratic Republic (Laos). CASE PRESENTATION: A 30 year-old female elementary school teacher and rice farmer from northeast Laos was admitted to Mahosot Hospital, Vientiane, with a massive growth on her left foot, without a history of trauma. The swelling had progressed slowly but painlessly over 5 years and multiple draining sinuses had developed. Ten days before admission the foot had increased considerably in size and became very painful, with multiple sinuses and discharge, preventing her from walking. Gram stain and bacterial culture of tissue biopsies revealed a branching filamentous Gram-positive bacterium that was subsequently identified as Actinomadura madurae by 16S rRNA gene amplification and sequencing. She was treated with long-term co-trimoxazole and multiple 3-week cycles of amikacin with a good therapeutic response. CONCLUSION: We report the first patient with actinomycetoma from Laos. The disease should be considered in the differential diagnosis of chronic skin and bone infections in patients from rural SE Asia.

Peacock SJ, Cheng AC, Currie BJ, Dance DAB. 2011. The use of positive serological tests as evidence of exposure to Burkholderia pseudomallei. Am J Trop Med Hyg, 84 (6), pp. 1021-1022. | Read more

Salam AP, Khan N, Malnick H, Kenna DTD, Dance DAB, Klein JL. 2011. Melioidosis acquired by traveler to Nigeria. Emerg Infect Dis, 17 (7), pp. 1296-1298. | Show Abstract | Read more

We describe melioidosis associated with travel to Nigeria in a woman with diabetes, a major predisposing factor for this infection. With the prevalence of diabetes projected to increase dramatically in many developing countries, the global reach of melioidosis may expand.

Ihekweazu C, Basarab M, Wilson D, Oliver I, Dance D, George R, Pebody R. 2010. Outbreaks of serious pneumococcal disease in closed settings in the post-antibiotic era: a systematic review. J Infect, 61 (1), pp. 21-27. | Show Abstract | Read more

SUMMARY OBJECTIVES: Since the introduction of antibiotics, pneumococcal disease is predominantly sporadic, with occasional outbreaks. Our objective was to review the epidemiology of reported outbreaks of serious pneumococcal disease in closed settings to inform the development of guidelines to manage such outbreaks. METHODS: We systematically reviewed the literature for reported outbreaks of serious pneumococcal disease in closed settings to inform the development of guidelines in managing such outbreaks. RESULTS: We identified 42 outbreaks reported in 39 papers---14 in hospitals, 12 in long term care facilities, five outbreaks in households, four in military settings, three in child care settings and two each in homeless shelters and jails. The serotype/group most frequently associated with outbreaks was 14 (seven outbreaks) followed by 4 (five outbreaks) then serotypes/groups 1, 9 and 9V each causing four outbreaks. The median outbreak size was four cases (2 - 46). The median duration was eight days, with 84% of cases occurring within 14 days of the first case. CONCLUSION: Outbreaks of serious pneumococcal disease are likely to continue happening requiring early recognition and implementation of public health measures in order to interrupt transmission. This study facilitated the development of the first UK interim guidelines for managing such outbreaks.

Nontprasert A, Cheeramakara C, Pukrittayakamee S, Dance DAB, Pitt TL, Smith MD, Vanijanonta S, White NJ. 2009. SDS-PAGE analysis of whole cell protein and outer membrane protein patterns of clinical isolates of Burkholderia pseudomallei ASIAN PACIFIC JOURNAL OF TROPICAL MEDICINE, 2 (5), pp. 14-19.

Smith MD, Sheppard CL, Hogan A, Harrison TG, Dance DAB, Derrington P, George RC, South West Pneumococcus Study Group. 2009. Diagnosis of Streptococcus pneumoniae infections in adults with bacteremia and community-acquired pneumonia: clinical comparison of pneumococcal PCR and urinary antigen detection. J Clin Microbiol, 47 (4), pp. 1046-1049. | Show Abstract | Read more

The diagnosis of severe Streptococcus pneumoniae infection relies heavily on insensitive culture techniques. To improve the usefulness of PCR assays, we developed a dual-PCR protocol (targeted at pneumolysin and autolysin) for EDTA blood samples. This was compared to the Binax NOW S. pneumoniae urine antigen test in patients with bacteremic pneumococcal infections. Patients with nonbacteremic community-acquired pneumonia also were tested by these methods to determine what proportion could be confirmed as pneumococcal infections. A direct comparison was made in a group of patients who each had both tests performed. The Binax NOW S. pneumoniae urine antigen test was positive in 51 of 58 bacteremic pneumococcal cases (sensitivity, 88%; 95% confidence interval [CI], 77 to 95%), whereas the dual PCR was positive in 31 cases (sensitivity, 53.5%; 95% CI, 40 to 67%; P < 0.0001), and all of these had detectable urinary antigens. Both tests gave positive results in 2 of 51 control patients (referred to as other-organism septicemia), giving a specificity of 96% (95% CI, 86.5 to 99.5%). In 77 patients with nonbacteremic community-acquired pneumonia, urinary antigen was detected significantly more often (in 21 patients [27%]) than a positive result by the dual-PCR protocol (6 [8%]) (P = 0.002). The development of a dual-PCR protocol enhanced the sensitivity compared to that of the individual assays, but it is still significantly less sensitive than the Binax NOW urine antigen test, as well as being more time-consuming and expensive. Urinary antigen detection is the nonculture diagnostic method of choice for patients with possible severe pneumococcal infection.

Currie BJ, Dance DAB, Cheng AC. 2008. The global distribution of Burkholderia pseudomallei and melioidosis: an update. Trans R Soc Trop Med Hyg, 102 Suppl 1 (SUPPL. 1), pp. S1-S4. | Show Abstract | Read more

While Southeast Asia and northern Australia are well recognized as the major endemic regions for melioidosis, recent reports have expanded the endemic zone. Severe weather events and environmental disasters such as the 2004 Asian tsunami have unmasked locations of sporadic cases and have reconfirmed endemicity in Indonesia. The endemic region now includes the majority of the Indian subcontinent, southern China, Hong Kong and Taiwan. Sporadic cases have occurred in Brazil and elsewhere in the Americas and in island communities such as New Caledonia, in the Pacific Ocean, and Mauritius in the Indian Ocean. Some of the factors that are critical to further elucidating the global distribution of Burkholderia pseudomallei and melioidosis include improved access to diagnostic laboratory facilities and formal confirmation of the identity of bacterial isolates from suspected cases.

Ihekweazu CA, Dance DAB, Pebody R, George RC, Smith MD, Waight P, Christensen H, Cartwright KAV, Stuart JM, South West Pneumococcus Study Group. 2008. Trends in incidence of pneumococcal disease before introduction of conjugate vaccine: South West England, 1996-2005. Epidemiol Infect, 136 (8), pp. 1096-1102. | Show Abstract | Read more

Introduction of pneumococcal conjugate and polysaccharide vaccines into the United Kingdom's routine immunization programmes is expected to change the epidemiology of invasive pneumococcal disease (IPD). We have documented the epidemiology of IPD in an English region (South West) with high-quality surveillance data before these programmes were established. We analysed data on isolates of Streptococcus pneumoniae from blood and CSF between 1996 and 2005 from microbiology laboratories in the South West that were reported and/or referred for serotyping to the Health Protection Agency Centre for Infections. The mean annual incidence of IPD increased from 11.2/100 000 in 1996 to 13.6/100 000 in 2005 (P<0.04). After adjusting for annual blood-culture sampling rates in hospitals serving the same catchment populations, an increase in annual incidence of IPD was no longer observed (P=1.0). Variation in overall incidence between laboratories could also be explained by variation in blood culture rates. The proportion of disease caused by serotypes 6B, 9V and 14 decreased significantly (P=0.001, P=0.007, and P=0.027 respectively) whereas that caused by serotype 4, 7F and 1 increased (P=0.001, P=0.003, and P<0.001 respectively) between 2000 and 2005. The level of penicillin non-susceptibility and resistance to erythromycin remained stable (2% and 12% respectively). This study provides an important baseline to assess the impact of changing vaccination programmes on the epidemiology of IPD, thus informing future use of pneumococcal vaccines.

Cheng AC, Chierakul W, Chaowagul W, Chetchotisakd P, Limmathurotsakul D, Dance DAB, Peacock SJ, Currie BJ. 2008. Consensus guidelines for dosing of amoxicillin-clavulanate in melioidosis. Am J Trop Med Hyg, 78 (2), pp. 208-209. | Show Abstract

Melioidosis is an infectious disease endemic to northern Australia and Southeast Asia. In response to clinical confusion regarding the appropriate dose of amoxicillin-clavulanate, we have developed guidelines for the appropriate dosing of this second-line agent. For eradication therapy for melioidosis, we recommend 20/5 mg/kg orally, three times daily.

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Cheng AC, Chierakul W, Chaowagul W, Chetchotisakd P, Limmathurotsakul D, Dance DAB, Peacock SJ, Currie BJ. 2008. Short report: Consensus guidelines for dosing of amoxicillin-clavulanate in melioidosis AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE, 78 (2), pp. 208-209. | Show Abstract

Melioidosis is an infectious disease endemic to northern Australia and Southeast Asia. In response to clinical confusion regarding the appropriate dose of amoxicillin-clavulanate, we have developed guidelines for the appropriate dosing of this second-line agent. For eradication therapy for melioidosis, we recommend 20/5 mg/kg orally, three times daily. Copyright © 2008 by The American Society of Tropical Medicine and Hygiene.

Peacock SJ, Schweizer HP, Dance DAB, Smith TL, Gee JE, Wuthiekanun V, DeShazer D, Steinmetz I, Tan P, Currie BJ. 2008. Management of accidental laboratory exposure to Burkholderia pseudomallei and B. mallei. Emerg Infect Dis, 14 (7), pp. e2. | Show Abstract | Read more

The gram-negative bacillus Burkholderia pseudomallei is a saprophyte and the cause of melioidosis. Natural infection is most commonly reported in northeast Thailand and northern Australia but also occurs in other parts of Asia, South America, and the Caribbean. Melioidosis develops after bacterial inoculation or inhalation, often in relation to occupational exposure in areas where the disease is endemic. Clinical infection has a peak incidence between the fourth and fifth decades; with diabetes mellitus, excess alcohol consumption, chronic renal failure, and chronic lung disease acting as independent risk factors. Most affected adults ( approximately 80%) in northeast Thailand, northern Australia, and Malaysia have >/=1 underlying diseases. Symptoms of melioidosis may be exhibited many years after exposure, commonly in association with an alteration in immune status. Manifestations of disease are extremely broad ranging and form a spectrum from rapidly life-threatening sepsis to chronic low-grade infection. A common clinical picture is that of sepsis associated with bacterial dissemination to distant sites, frequently causing concomitant pneumonia and liver and splenic abscesses. Infection may also occur in bone, joints, skin, soft tissue, or the prostate. The clinical symptoms of melioidosis mimic those of many other diseases; thus, differentiating between melioidosis and other acute and chronic bacterial infections, including tuberculosis, is often impossible. Confirmation of the diagnosis relies on good practices for specimen collection, laboratory culture, and isolation of B. pseudomallei. The overall mortality rate of infected persons is 50% in northeast Thailand (35% in children) and 19% in Australia.

Currie BJ, Thomas AD, Godoy D, Dance DA, Cheng AC, Ward L, Mayo M, Pitt TL, Spratt BG. 2007. Australian and Thai isolates of Burkholderia pseudomallei are distinct by multilocus sequence typing: revision of a case of mistaken identity. J Clin Microbiol, 45 (11), pp. 3828-3829. | Show Abstract | Read more

A recent study using multilocus sequence typing (MLST) of Burkholderia pseudomallei isolates found a sequence type (ST60) to be common to both Thailand and Australia, contradicting earlier studies showing complete distinction between isolates from these regions. The ST60 isolates reportedly from Australia had been obtained for MLST from United Kingdom and U.S. collections. We have located and characterized the original Australian isolates; they were collected in 1983, and they are neither ST60 nor B. pseudomallei isolates. The B. pseudomallei MLST database has been corrected, and there is no ST common to isolates verified as obtained from Australia or from Thailand.

Pitt TL, Trakulsomboon S, Dance DAB. 2007. Recurrent melioidosis: possible role of infection with multiple strains of Burkholderia pseudomallei. J Clin Microbiol, 45 (2), pp. 680-681. | Read more

Brent AJ, Matthews PC, Dance DA, Pitt TL, Handy R. 2007. Misdiagnosing melioidosis. Emerg Infect Dis, 13 (2), pp. 349-351. | Read more

Orr HJ, Christensen H, Smyth B, Dance DAB, Carrington D, Paul I, Stuart JM, South West Q Fever Project Group. 2006. Case-control study for risk factors for Q fever in southwest England and Northern Ireland. Euro Surveill, 11 (10), pp. 260-262. | Show Abstract

Q fever (Coxiella burnetti) is thought to account for 1% (700 cases) of community acquired pneumonia in the United Kingdom each year, and can result in serious complications such as endocarditis. Although outbreaks have frequently been reported worldwide, the causes are often not clearly identified and there have been few studies of risk factors in sporadic cases. We conducted a matched case-control study. Cases of acute Q fever in people aged over 15 years in southwest England and Northern Ireland were identified from January 2002 to December 2004. Controls were matched for age, sex and the general practice at which they were registered. Questionnaires asking about contact with animals, and leisure and work activities, were posted to cases and controls. Questionnaires were completed by 39/50 (78%) of the cases and 90/180 (50%) of the controls. In the single variable analysis, occupational exposure to animals or animal products was the only risk factor associated with cases at the 5% level (P=0.05, odds ratio (OR) 3.4). Long term illness appeared to be significantly protective (P=0.03, OR 0.3). In multivariable analysis the strength of association between occupational exposure and illness remained high (OR 3.6, 95% confidence interval (CI) 0.9 to 14.8) and smoking emerged as a possible risk factor. This is the first case-control study to identify occupational exposure to animals or animal products as the most likely route of infection in sporadic cases as opposed to outbreaks.

Chierakul W, Wangboonskul J, Singtoroj T, Pongtavornpinyo W, Short JM, Maharjan B, Wuthiekanun V, Dance DAB, Teparrukkul P, Lindegardh N et al. 2006. Pharmacokinetic and pharmacodynamic assessment of co-amoxiclav in the treatment of melioidosis. J Antimicrob Chemother, 58 (6), pp. 1215-1220. | Show Abstract | Read more

OBJECTIVES: We conducted a prospective pharmacokinetic study of oral co-amoxiclav in patients with melioidosis to determine the optimal dosage and dosing interval in this potentially fatal infection. PATIENTS AND METHODS: Serial plasma concentrations were measured after administration of two 1 g tablets of Augmentin (1750 mg of amoxicillin and 250 mg of clavulanate) to 14 adult patients with melioidosis. Monte Carlo simulation was used to predict the concentration of each drug following multiple doses of co-amoxiclav at different dosages and dose intervals. The proportion of the dose-interval above MIC (T > MIC) was calculated from 10,000 simulated subject plasma concentration profiles together with chequerboard MIC data from 46 clinical isolates and four reference strains of Burkholderia pseudomallei. RESULTS: The median (range) observed maximum plasma concentrations of amoxicillin and clavulanate were 11.5 (3.3-40.2) mg/L and 5.1 (0.8-12.1) mg/L, respectively. The median (range) elimination half-lives were 94 (73-215) and 89 (57-140) min, respectively. Simulation indicated that co-amoxiclav 1750/250 mg given at 4, 6, 8 or 12 hourly dosing intervals would be associated with a T > MIC of < or = 50% in 0.7%, 2.8%, 8.6% and 33.2% of patients, respectively. Corresponding proportions for T > MIC of > or = 90% were 95.8%, 78.6%, 50.2% and 10.8%, respectively. CONCLUSIONS: The dosing interval for co-amoxiclav (750/250 mg) in melioidosis should not be greater than 6 h.

Mahfouz ME, Grayson TH, Dance DAB, Gilpin ML. 2006. Characterization of the mrgRS locus of the opportunistic pathogen Burkholderia pseudomallei: temperature regulates the expression of a two-component signal transduction system. BMC Microbiol, 6 pp. 70. | Show Abstract | Read more

BACKGROUND: Burkholderia pseudomallei is a saprophyte in tropical environments and an opportunistic human pathogen. This versatility requires a sensing mechanism that allows the bacterium to respond rapidly to altered environmental conditions. We characterized a two-component signal transduction locus from B. pseudomallei 204, mrgR and mrgS, encoding products with extensive homology with response regulators and histidine protein kinases of Escherichia coli, Bordetella pertussis, and Vibrio cholerae. RESULTS: The locus was present and expressed in a variety of B. pseudomallei human and environmental isolates but was absent from other Burkholderia species, B. cepacia, B. cocovenenans, B. plantarii, B. thailandensis, B. vandii, and B. vietnamiensis. A 2128 bp sequence, including the full response regulator mrgR, but not the sensor kinase mrgS, was present in the B. mallei genome. Restriction fragment length polymorphism downstream from mrgRS showed two distinct groups were present among B. pseudomallei isolates. Our analysis of the open reading frames in this region of the genome revealed that transposase and bacteriophage activity may help explain this variation. MrgR and MrgS proteins were expressed in B. pseudomallei 204 cultured at different pH, salinity and temperatures and the expression was substantially reduced at 25 degrees C compared with 37 degrees C or 42 degrees C but was mostly unaffected by pH or salinity, although at 25 degrees C and 0.15% NaCl a small increase in MrgR expression was observed at pH 5. MrgR was recognized by antibodies in convalescent sera pooled from melioidosis patients. CONCLUSION: The results suggest that mrgRS regulates an adaptive response to temperature that may be essential for pathogenesis, particularly during the initial phases of infection. B. pseudomallei and B. mallei are very closely related species that differ in their capacity to adapt to changing environmental conditions. Modifications in this region of the genome may assist our understanding of the reasons for this difference.

Dance D. 2005. A glanders-like disease in Rangoon: Whitmore A. J Hyg 1913; 13: 1-34. Epidemiol Infect, 133 Suppl 1 (S1), pp. S9-S10. | Read more

Peacock SJ, Chieng G, Cheng AC, Dance DAB, Amornchai P, Wongsuvan G, Teerawattanasook N, Chierakul W, Day NPJ, Wuthiekanun V. 2005. Comparison of Ashdown's medium, Burkholderia cepacia medium, and Burkholderia pseudomallei selective agar for clinical isolation of Burkholderia pseudomallei. J Clin Microbiol, 43 (10), pp. 5359-5361. | Show Abstract | Read more

Ashdown's medium, Burkholderia pseudomallei selective agar (BPSA), and a commercial Burkholderia cepacia medium were compared for their abilities to grow B. pseudomallei from 155 clinical specimens that proved positive for this organism. The sensitivity of each was equivalent; the selectivity of BPSA was lower than that of Ashdown's or B. cepacia medium.

Cheng AC, Dance DA, Currie BJ. 2005. Bioterrorism, Glanders and melioidosis. Euro Surveill, 10 (3), pp. 11-12. | Show Abstract | Read more

We note with interest the recently published guidelines for management of melioidosis and glanders. We are clinicians with extensive experience with melioidosis in Australia and Thailand and would like to express our concern at a number of inaccuracies in these guidelines.

Cheng AC, Dance DAB, Currie BJ. 2005. Bioterrorism, Glanders and melioidosis. Euro Surveill, 10 (3), pp. E1-E2.

McNulty CAM, Coleman T, Telfer-Brunton A, Dance D, Smith M, Jacobson K. 2003. How should laboratories communicate with primary care? Obtaining general practitioners' views. J Infect, 47 (2), pp. 99-103. | Show Abstract | Read more

AIMS: Recognising the importance of communication with our primary care colleagues, focus groups were held with GPs to determine how they perceived the current lines of communication with their local microbiology laboratory and the PHLS, and how they could be improved. METHODS: Focus groups were held in Plymouth, Gloucester, Bristol and Hereford. Between four and 10 GPs and/or PCG Board members attended each workshop. The modes of communication i.e. websites, face-to-face contact, laboratory reporting, telephone advice, newsletters, guidance and surveillance were discussed. RESULTS: Microbiology websites should be user friendly, with clear labelling as to whom the page is directed. They should contain locally relevant data, antibiotic guidance and information leaflets. Despite great variation in laboratory reporting protocols GPs were mostly happy with reports received. Results, especially serology, should contain a clear conclusion and could refer to a website for further information. Electronic reporting was enthusiastically awaited. All GPs felt they had excellent access to telephone advice. GPs would value data and guidance on their use of diagnostic tests. CONCLUSION: These workshops highlight the variation in laboratory reporting protocols that should be addressed. Website development for GPs should include locally relevant data. GPs would value details of their laboratory use and costs.

Johnson AP, Henwood C, Mushtaq S, James D, Warner M, Livermore DM, ICU Study Group. 2003. Susceptibility of Gram-positive bacteria from ICU patients in UK hospitals to antimicrobial agents. J Hosp Infect, 54 (3), pp. 179-187. | Show Abstract | Read more

Microbiologists in 25 sentinel laboratories were each asked to refer up to 100 clinically-significant Gram-positive bacteria isolated from consecutive intensive care unit (ICU) patients. A total of 1595 isolates were collected from patients in 23 hospitals; these included Staphylococcus aureus (47.6%), coagulase-negative staphylococci (CNS) (30.6%), enterococci (14.3%), pneumococci (2.8%) and other streptococci (3.5%). A few coryneforms, other bacilli and a Nocardia sp. were also collected. Rates of oxacillin resistance among S. aureus and CNS isolates were 59.3 and 78.5%, respectively. Vancomycin-resistant S. aureus were not detected, although two isolates (0.3%) were resistant to teicoplanin [minimum inhibitory concentrations (MICs) 8 mg/L]. In contrast, 13.7% of CNS were teicoplanin resistant (MICs 8-32 mg/L) and 1.2% were resistant to vancomycin. Among the enterococci, 72.5% were Enterococcus faecalis and 24.5% were Enterococcus faecium, the remainder including isolates of Enterococcus casseliflavus or Enterococcus gallinarum. Eighteen percent of E. faecium isolates were vancomycin-resistant, compared with only 3% of E. faecalis isolates. Rates of high-level gentamicin resistance in E. faecalis and E. faecium were 40 and 25%, respectively. Nine percent of pneumococci and streptococci were resistant to penicillin, with 7 and 11%, respectively, resistant to erythromycin. None of the isolates showed resistance to linezolid, with the MICs for the entire study population falling in the range of 0.5-4 mg/L.

Smith MD, Derrington P, Evans R, Creek M, Morris R, Dance DAB, Cartwright K. 2003. Rapid diagnosis of bacteremic pneumococcal infections in adults by using the Binax NOW Streptococcus pneumoniae urinary antigen test: a prospective, controlled clinical evaluation. J Clin Microbiol, 41 (7), pp. 2810-2813. | Show Abstract | Read more

The diagnosis of severe pneumococcal infections is inadequate, relying heavily on culture of Streptococcus pneumoniae from blood or other normally sterile fluids, and is severely limited by prior administration of antibiotics. We evaluated prospectively the Binax NOW S. pneumoniae urinary antigen test, a rapid immunochromatographic assay, for the diagnosis of bacteremic pneumococcal infections in hospitalized adult patients. Antigen was detected in 88 of 107 cases overall, resulting in a test sensitivity of 82% (95% confidence interval [95% CI], 74 to 89%). Antigen detection was greater in those with pneumonia (67 of 77 [87%]) than in those without pneumonia (21 of 30 [70%]) (P = 0.04). Urinary antigen was also detected in 3 of 106 adult patients with community-acquired septicemic infections caused by other organisms, giving a test specificity of 97% (95% CI, 92 to 99%). For 45 pneumococcal bacteremia patients with a positive test on treatment day 1, urinary antigen excretion was monitored for the first week of antibiotic treatment. Antigen was still detectable in 83% (29 of 35 tested; 95% CI, 66 to 93%) on treatment day 3. Detection of urinary antigen is a valuable, sensitive, and rapid test for the early diagnosis of bacteremic pneumococcal infections in adult patients, even after antibiotic treatment has commenced.

Dance DAB. 2002. Better systems are still needed. Hosp Med, 63 (9), pp. 519.

Jacobs A. 2002. Immunity conferred by smallpox vaccine. How long does immunity last? BMJ, 324 (7346), pp. 1157. | Read more

Beeching NJ, Dance DAB, Miller ARO, Spencer RC. 2002. Immunity conferred by smallpox vaccine - How long does immunity last? Reply BRITISH MEDICAL JOURNAL, 324 (7346), pp. 1157-1158.

Dance DAB. 2002. Melioidosis. Curr Opin Infect Dis, 15 (2), pp. 127-132. | Show Abstract | Read more

Melioidosis is an important public health problem in some regions, and a potential bioweapon. Recent reports confirm that it is endemic in China, Taiwan and Laos, but the true incidence in most countries is unknown, and the ecology poorly understood. Potable water was the source of two recent outbreaks. The epidemiology and clinical manifestations of the disease in Australia are similar to those in Thailand, although prostatic abscesses and neurological manifestations are more common and parotid abscesses less so. Mycotic aneurysms are not uncommon. Patients with cystic fibrosis are at risk of pulmonary melioidosis. Comparison with the avirulent Burkholderia thailandensis has identified capsular polysaccharide as an important virulence determinant in Burkholderia pseudomallei. Diagnosis still relies on culture, and a throat swab is a worthwhile sample. Several beta-lactams, such as meropenem, reduce the mortality, and long courses of cotrimoxazole-containing regimes are needed to prevent relapse. The value of adjunctive treatments, such as granulocyte colony-stimulating factor, warrants further evaluation.

Beeching NJ, Dance DAB, Miller ARO, Spencer RC. 2002. Biological warfare and bioterrorism. BMJ, 324 (7333), pp. 336-339. | Read more

Harrison SL, Nelder R, Hayek L, Mackenzie IF, Casemore DP, Dance D. 2002. Managing a large outbreak of cryptosporidiosis: how to investigate and when to decide to lift a 'boil water' notice. Commun Dis Public Health, 5 (3), pp. 230-239. | Show Abstract

The largest outbreak of cryptosporidiosis reported in the United Kingdom, involving 575 confirmed cases (of which 474 met an agreed case definition), occurred in the county of Devon during August and September of 1995. The descriptive epidemiology supports the hypothesis that the outbreak was associated with the consumption of cold tap water in the area served by a particular water treatment works. Cryptosporidium oocysts were detected in treated water samples at the time of the outbreak. Although the epidemiological analysis provided strong circumstantial evidence of a waterborne outbreak, the data were not recorded in a manner that made them admissible in criminal proceedings taken by the Drinking Water Inspectorate against the water company involved. The need to carry out an analytical study in conjunction with the identification and characterisation of the pathogen in the drinking water and the practicalities of agreeing criteria for lifting a 'boil water' notice are discussed.

Langsford MJ, Dobbs FF, Morrison GM, Dance DA. 2001. The effect of introduction of a guideline on the management of vaginal discharge and in particular bacterial vaginosis in primary care. Fam Pract, 18 (3), pp. 253-257. | Show Abstract | Read more

BACKGROUND: Bacterial vaginosis (BV) is the commonest cause of vaginal discharge, and its association with obstetric and gynaecological complications is being recognized increasingly. It was our impression that BV was poorly understood and underdiagnosed in family practice. OBJECTIVE: The aim of this study was to explore the management of patients with vaginal symptoms by family practitioners and to see if the management changed after the assimilation of best practice guidelines. METHOD: Family practitioners were invited to complete a baseline questionnaire of their perceived practice, and to record actual practice when consulted about vaginal symptoms, for a minimum of 4 weeks. Consensus best practice guidelines were then provided and practice recorded for a similar period. RESULTS: Baseline data was received from 34 practitioners and suggested that the symptoms and signs of different vaginal infections were not well known. Most symptomatic patients were only investigated at re-presentation with unresolved symptoms or at recurrence, and 43% of respondents treated with empirical antifungals as a first line approach. Pregnant patients were only occasionally asked about symptoms and only occasionally examined if symptomatic. Pre-guideline practice data from 30 practitioners showed 1.2 patient consultations/week, of which 60% were examined and 55% had a high vaginal swab (HVS) sent. Only 2% had near-patient tests done. Post-guideline data from 23 family practitioners showed a lower recorded consultation rate at 0.7/week, but 90% of these were examined, 77% had an HVS sent and 69% had near-patient tests done. Of the 36 HVS examined by Gram stain, 19 (53%) showed Lactobacillus predominant flora and 10 (28%) suggested BV. Seven (19%) were borderline or ungradable. Only three (8%) showed yeasts, one of which also showed BV. CONCLUSIONS: Baseline data supported our impression that BV was under-recognized. Guidelines appeared to improve the rate of investigation of women consulting with vaginal symptoms.

Henwood CJ, Livermore DM, James D, Warner M, Pseudomonas Study Group. 2001. Antimicrobial susceptibility of Pseudomonas aeruginosa: results of a UK survey and evaluation of the British Society for Antimicrobial Chemotherapy disc susceptibility test. J Antimicrob Chemother, 47 (6), pp. 789-799. | Show Abstract | Read more

A survey was conducted in 1999, first to establish the prevalence of antibiotic resistance among clinical isolates of Pseudomonas aeruginosa in the UK and secondly to test whether the use of the standardized British Society for Antimicrobial Chemotherapy (BSAC) disc testing method improved the accuracy of routine susceptibility testing for this organism. Twenty-five hospitals were each asked to collect up to 100 consecutive, clinically significant isolates of P. aeruginosa and to test their susceptibility to amikacin, gentamicin, ceftazidime, imipenem, meropenem, ciprofloxacin, piperacillin and piperacillin/tazobactam using the new BSAC disc method. A total of 2194 isolate reports were available for analysis and 10% of the isolates represented, plus those with unusual resistances, were re-tested centrally for quality control purposes. The zone distributions were essentially unimodal, indicating the absence of major populations with acquired resistance. The results indicated that resistance rates to the beta-lactam, aminoglycoside and quinolone agents tested in P. aeruginosa in the UK remain low (<12%), and were mostly unchanged since a previous survey conducted in 1993. High resistance rates were nevertheless reported for isolates from cystic fibrosis patients. The accuracy of susceptibility testing using the new BSAC disc testing method was better than in previous studies, when Stokes' method was most frequently used. Critically, the proportion of resistant isolates incorrectly reported as susceptible was reduced significantly; nevertheless, depending on the antibiotic, up to 49% of the isolates reported as intermediate or resistant were found susceptible on central re-testing.

Dance DA. 2000. Melioidosis as an emerging global problem. Acta Trop, 74 (2-3), pp. 115-119. | Show Abstract | Read more

There is remarkably little known about the incidence of melioidosis outside a few countries (Thailand, Australia, Singapore and Malaysia). Presumably it is widespread in tropical south east Asia. Elsewhere there are tantalising glimpses of the tip of what may be a large iceberg. Since a specific diagnosis of melioidosis requires awareness on the part of clinicians, and the existence of a laboratory capable of isolating and identifying Burkholderia pseudomallei, a luxury not available in most rural tropical areas, the size of this iceberg is likely to remain unknown for the foreseeable future. There is mounting evidence that the disease is endemic in the Indian sub-continent and the Caribbean, and there have been unsubstantiated reports of recent cases in South Africa and the Middle East. It is unclear whether melioidosis has really spread to such areas relatively recently, or has been there but unrecognised for a long time. Almost all cases diagnosed in temperate climates have been imported from the tropics, with the exception of a unique outbreak which occurred in France in the mid-1970s. With increasing world wide travel of both humans and other animals, the potential exists for melioidosis to spread to new and fertile pastures.

Dance DA. 2000. Ecology of Burkholderia pseudomallei and the interactions between environmental Burkholderia spp. and human-animal hosts. Acta Trop, 74 (2-3), pp. 159-168. | Show Abstract | Read more

Early workers thought that melioidosis was a zoonosis with a reservoir in rodents, but we now know that Burkholderia pseudomallei is a widely distributed environmental saprophyte. In northeast Thailand, two thirds of paddy fields yield the organism, and 80% of children have antibodies by the time they are 4 years old. However, interpretation of these results has been complicated by the recent recognition of avirulent, antigenically cross-reacting environmental organisms for which the name B. thailandensis has been proposed. We still know very little about the climatic, physical, chemical and biological factors which control the proliferation and survival of Burkholderia spp. in the environment, although epidemiological studies show space-time clustering of melioidosis. It is assumed that most human and animal melioidosis arises through exposure to contaminated soil or muddy water, although only 6% of human cases have a clear history of inoculation, and a further 0.5% of cases follow near-drowning. Laboratory animals have also been infected by ingestion, inhalation and insect bites, but evidence of infection acquired naturally by these routes remains anecdotal. Sporadic cases have resulted from iatrogenic inoculation, laboratory accidents, and person-to-person or animal-to-person spread. Whether exposure to B. pseudomallei will result in disease probably depends on the balance between the virulence of the strain, the immune status of the host (e.g. diabetes mellitus) and the size of the inoculum.

Rahman M, Sanderson PJ, Bentley AH, Barrett SP, Karim QN, Teare EL, Chaudhuri A, Alcock SR, Corcoran GD, Azadian B et al. 2000. Control of MRSA. J Hosp Infect, 44 (2), pp. 151-153.

Henwood CJ, Livermore DM, Johnson AP, James D, Warner M, Gardiner A. 2000. Susceptibility of gram-positive cocci from 25 UK hospitals to antimicrobial agents including linezolid. The Linezolid Study Group. J Antimicrob Chemother, 46 (6), pp. 931-940. | Show Abstract

The prevalence of antibiotic resistance amongst Gram-positive cocci from 25 UK hospitals was studied over an 8 month period in 1999. A total of 3770 isolates were tested by the sentinel laboratories using the Etest; these bacteria comprised 1000 pneumococci, 1005 Staphylococcus aureus, 769 coagulase-negative staphylococci (CNS) and 996 enterococci. To ensure quality, 10% of the isolates were retested centrally, as were any found to express unusual resistance patterns. The prevalence of penicillin-resistant Streptococcus pneumoniae, vancomycin-resistant enterococci and methicillin-resistant S. aureus (MRSA) varied widely amongst the sentinel laboratories. The resistance rates to methicillin among S. aureus and CNS were 19.2 and 38.9%, respectively, with MRSA rates in individual sentinel sites ranging from 0 to 43%. No glycopeptide resistance was seen in S. aureus, but 6.5% of CNS isolates were teicoplanin resistant and 0.5% were vancomycin resistant. Vancomycin resistance was much more frequent among Enterococcus faecium (24.1%) than E. faecalis (0.5%) (P<0.05), with most resistant isolates carrying vanA. The rate of penicillin resistance in pneumococci was 8.9%, and this resistance was predominantly intermediate (7.9%), with only six hospitals reporting isolates with high level resistance. The prevalence of erythromycin resistance among pneumococci was 12.3%, with the majority of resistant isolates having the macrolide efflux mechanism mediated by mefE. All the organisms tested were susceptible to linezolid with MICs in the range 0.12-4 mg/L. The modal MICs of linezolid were 1 mg/L for CNS and pneumococci, and 2 mg/L for S. aureus and enterococci. Linezolid was the most potent agent tested against Gram-positive cocci, including multiresistant strains, and as such may prove a valuable therapeutic option for the management of Gram-positive infections in hospitals.

Dance DA. 2000. Burkholderia pseudomallei infections. Clin Infect Dis, 30 (1), pp. 235-236. | Read more

Simpson AJ, Dance DA, Wuthiekanun V, White NJ. 2000. Serum bactericidal and inhibitory titres in the management of melioidosis. J Antimicrob Chemother, 45 (1), pp. 123-127. | Show Abstract | Read more

A retrospective evaluation of the relationship between serum bactericidal and inhibitory titres and treatment outcome in 195 adult Thai patients with severe melioidosis was conducted. Drug regimens included ceftazidime (52% of patients), co-amoxiclav (24%), imipenem (11%) or the conventional four-drug combination (11%). Pre- and 1 h post-dose serum samples were collected after 48-72 h of therapy, and serum inhibitory and bactericidal titrations determined. Median post-dose titres were: bactericidal 1:8 (range 0-1:128) and inhibitory 1:16 (range 0-1:128). Overall mortality was 26% and outcome was not influenced by either inhibitory or bactericidal titres. Pre-dose titres correlated with renal function; renal function was the most important predictor of mortality. Determination of serum inhibitory or bactericidal titres is unhelpful in the management of severe melioidosis.

Santanirand P, Harley VS, Dance DA, Drasar BS, Bancroft GJ. 1999. Obligatory role of gamma interferon for host survival in a murine model of infection with Burkholderia pseudomallei. Infect Immun, 67 (7), pp. 3593-3600. | Show Abstract

Burkholderia pseudomallei, the causative agent of melioidosis, is a gram-negative bacterium capable of causing either acute lethal sepsis or chronic but eventually fatal disease in infected individuals. However, despite the clinical importance of this infection in areas where it is endemic, there is essentially no information on the mechanisms of protective immunity to the bacterium. We describe here a murine model of either acute or chronic infection with B. pseudomallei in Taylor Outbred (TO) mice which mimics many features of the human pathology. Intraperitoneal infection of TO mice at doses of >10(6) CFU resulted in acute septic shock and death within 2 days. In contrast, at lower doses mice were able to clear the inoculum from the liver and spleen over a 3- to 4-week period, but persistence of the organism at other sites resulted in a chronic infection of between 2 and 16 months duration which was eventually lethal in all of the animals tested. Resistance to acute infection with B. pseudomallei was absolutely dependent upon the production of gamma interferon (IFN-gamma) in vivo. Administration of neutralizing monoclonal antibody against IFN-gamma lowered the 50% lethal dose from >5 x 10(5) to ca. 2 CFU and was associated with 8,500- and 4,400-fold increases in the bacterial burdens in the liver and spleen, respectively, together with extensive destruction of lymphoid architecture in the latter organ within 48 h. Neutralization of either tumor necrosis factor alpha or interleukin-12 but not granulocyte-macrophage colony-stimulating factor, also increased susceptibility to infection in vivo. Together, these results provide the first evidence of a host protective mechanism against B. pseudomallei. The rapid production of IFN-gamma within the first day of infection determines whether the infection proceeds to an acute lethal outcome or becomes chronic.

McLarty E, Dance DA. 1999. Adverse effects of being a "healthy carrier". Lancet, 353 (9171), pp. 2246-2247. | Read more

Rahman M, Sanderson PJ, Bentley AH, Barrett SP, Karim QN, Teare EL, Chaudhuri A, Alcock SR, Corcoran GD, Azadian B et al. 1999. Revised guidelines for control of MRSA in hospitals: finding the most useful point. J Hosp Infect, 42 (1), pp. 71-72.

Bombieri L, Dance DA, Rienhardt GW, Waterfield A, Freeman RM. 1999. Urinary tract infection after urodynamic studies in women: incidence and natural history. BJU Int, 83 (4), pp. 392-395. | Show Abstract | Read more

OBJECTIVE: To study the incidence, natural history and symptomatic effects of bacteriuria after urodynamic studies in women. PATIENTS AND METHODS: In a prospective study in the urogynaecology clinic of a large District General Hospital, 214 women (mean age 52.3 years, range 23-81) underwent urodynamic studies. Bacteriuria was detected by semiquantitative culture at 2 and 7 days after the test. Women completed a 7-day diary of symptoms and events. RESULTS: The incidence of bacteriuria after urodynamic studies was 7.9%. Bacteriuria was transient in four of 17 women but persisted in nine and developed late in four; only one of 17 infections gave rise to symptoms. Irritative bladder symptoms after the test occurred in 34% of women, but only three went to their doctors because of concern about a possible urinary tract infection. Advancing age was the only variable associated with bacteriuria after urodynamic studies (P= 0.05). Menopausal status, past history of urinary tract infection, number of urethral instrumentations required, order number in a session, peak urinary flow rate and urodynamic diagnosis were not associated variables. CONCLUSIONS: In a large series of women presenting to a urogynaecology clinic, urodynamic investigations were associated with a high incidence of transient irritative symptoms but a low incidence of bacteriuria (8%). Infection was asymptomatic in most patients, but its natural history was unpredictable. Transient, persistent and late cases of bacteriuria all occurred. In this population, urodynamic studies are associated with a low level of morbidity.

Dance DA, Smith MD, Aucken HM, Pitt TL. 1999. Imported melioidosis in England and Wales. Lancet, 353 (9148), pp. 208. | Read more

Vadivelu J, Puthucheary SD, Drasar BS, Dance DA, Pitt TL. 1998. Stability of strain genotypes of Burkholderia pseudomallei from patients with single and recurrent episodes of melioidosis. Trop Med Int Health, 3 (7), pp. 518-521. | Show Abstract | Read more

The constancy of strain genotypes of multiple isolates of Burkholderia pseudomallei from 13 patients with melioidosis was examined by BamHI ribotyping and pulsed-field gel electrophoresis (PFGE) of XbaI digests of DNA. Seven of 8 patients with single episodes of melioidosis each yielded genetically identical isolates and only one of five patients with recurrent episodes was infected with a new strain clearly distinct from the original primary strain. Variation was observed in PFGE patterns of primary and relapse isolates of another patient but this was insufficient to define genetically distinct strains. We conclude that most patients with single or multiple episodes of melioidosis retain a single strain.

Harley VS, Dance DA, Drasar BS, Tovey G. 1998. Effects of Burkholderia pseudomallei and other Burkholderia species on eukaryotic cells in tissue culture. Microbios, 96 (384), pp. 71-93. | Show Abstract

Burkholderia pseudomallei causes melioidosis, a serious and often fatal bacterial infection. B. pseudomallei can behave as a facultatively intracellular organism and this ability may be important in the pathogenesis of both acute and chronic infection. The uptake of B. pseudomallei and other Burkholderia spp. by cells in tissue culture was examined by electron microscopy. B. pseudomallei can invade cultured cell lines including phagocytic lines such as RAW264, J774 and U937, and non-phagocytic lines such as CaCO-2, Hep2, HeLa, L929, McCoy, Vero and CHO. Uptake was followed by the intracellular multiplication of B. pseudomallei and the induction of cell fusion and multinucleate giant cell formation. Similar effects were produced by B. mallei and B. thailandensis.

Harley VS, Dance DA, Tovey G, McCrossan MV, Drasar BS. 1998. An ultrastructural study of the phagocytosis of Burkholderia pseudomallei. Microbios, 94 (377), pp. 35-45. | Show Abstract

Burkholderia pseudomallei causes melioidosis and is believed to be an intracellular pathogen in human and animal disease. The uptake of B. pseudomallei by mouse peritoneal macrophages and cells in tissue culture was examined by electron microscopy. In all the systems studied B. pseudomallei were phagocytosed and apparently inhibited the normal processes of intracellular killing. Destruction of the phagosome membrane occurred and the bacteria escaped into the cytoplasm.

Philp R, McCann R, Rowland P. 1997. Is it time to stop searching for MRSA? Follow up screening within the community needs clarification. BMJ, 315 (7099), pp. 57. | Read more

Dance DA, Cunningham R, Gaunt PN, Stewart VJ, Swales J. 1997. Is it time to stop searching for MRSA? Environmental hygiene is an important part of control. BMJ, 315 (7099), pp. 59-60.

Trakulsomboon S, Dance DA, Smith MD, White NJ, Pitt TL. 1997. Ribotype differences between clinical and environmental isolates of Burkholderia pseudomallei. J Med Microbiol, 46 (7), pp. 565-570. | Show Abstract | Read more

Burkholderia pseudomallei is isolated frequently from the soil in regions where the disease melioidosis occurs. However, recent surveys in Thailand have shown that the frequency of isolation of the organism from soil samples is not directly related to the incidence of melioidosis in an area. To determine whether strain populations of B. pseudomallei prevalent in soil are gentypically related to strains causing clinical disease, rRNA BamHI restriction fragment length polymorphisms (RFLP) of 139 soil environmental isolates and 228 human isolates were compared. Two groups of ribotype patterns were found. Group I comprised 37 different ribotype patterns which were characterised by five to eight hybridisation bands of 2.8- > 23 kb. All of these ribotypes were identified among the clinical isolates, and 18 of them were also found in 59 environmental isolates. Group II was represented by 12 ribotypes found only in environmental strains. These ribotype patterns comprised one to five bands in the size range 9- > 23 kb. All but one of the 73 isolates in this group grew on a minimal medium supplemented with L-arabinose. In contrast, only 3% of the 66 isolates from the environment with group I ribotype patterns could utilise this sugar as their sole energy source. These findings suggest that B. pseudomallei strains that utilise arabinose constitute a population that is genetically distinct from other environmental and clinical strains.

Acharya GP, Davis TM, Ho M, Harris S, Chataut C, Acharya S, Tuhladar N, Kafle KE, Pokhrel B, Nosten F et al. 1997. Factors affecting the pharmacokinetics of parenteral chloramphenicol in enteric fever. J Antimicrob Chemother, 40 (1), pp. 91-98. | Show Abstract | Read more

Chloramphenicol pharmacokinetics were studied in 29 Nepalese adults diagnosed with uncomplicated enteric fever and randomized to receive succinate ester 30 mg/kg i.v. or i.m. Serial plasma concentrations of chloramphenicol, and iothalamate (to estimate glomerular filtration rate), antipyrine (hepatocellular function) and Indocyanine Green (liver blood flow) were measured by HPLC and kinetic parameters estimated by non-compartmental analysis. In culture-positive patients (n = 16), mean residence times (MRTs) and steady-state volumes of distribution (V(d)ss) for i.v. chloramphenicol (mean +/- S.D.; 4.9 +/- 0.9 h and 1.9 +/- 0.8 L/kg; n = 7) were less than after i.m. chloramphenicol (12.3 +/- 7.3 h and 3.7 +/- 2.5 L/kg; n = 9; P < 0.05), with a higher peak plasma concentration after i.v. (16.2 +/- 9.1 versus 7.8 +/- 3.6 mg/L; P < 0.05); plasma clearance (Cl(p)) was similar in the two groups (368 +/- 172 and 310 +/- 224 mL/kg/min after i.v. and i.m. respectively). In 17 patients examined during convalescence, MRT and Vdss were less than in acute illness regardless of route chloramphenicol administration. There were similar changes in chloramphenicol kinetic parameters in culture-negative patients. Antipyrine Cl(p) and liver blood flow correlated weakly with chloramphenicol Cl(p) in culture-positive patients (P < 0.1) and were higher in convalescence; no such associations were seen for iothalamate Cl(p). These data indicate that i.v. chloramphenicol produces peak plasma concentrations which are on average twice those after i.m. injection of the same dose, due principally to a smaller V(d)ss. Cl(p) is uninfluenced by route of administration and is determined more by hepatic metabolism than renal excretion. Intramuscular treatment may result in sub-therapeutic chloramphenicol concentrations initially, but continued regular i.v. dosing is more likely to produce levels at which bone marrow toxicity occurs.

Santanirand P, Harley VS, Dance DA, Raynes JG, Drasar BS, Bancroft GJ. 1997. Interferon-gamma mediates host resistance in a murine model of melioidosis. Biochem Soc Trans, 25 (2), pp. 287S. | Read more

Vadivelu J, Puthucheary SD, Mifsud A, Drasar BS, Dance DA, Pitt TI. 1997. Ribotyping and DNA macrorestriction analysis of isolates of Burkholderia pseudomallei from cases of melioidosis in Malaysia. Trans R Soc Trop Med Hyg, 91 (3), pp. 358-360. | Show Abstract | Read more

Forty-nine isolates of Burkholderia pseudomallei from sporadic cases of melioidosis in Malaysia over the past 18 years were examined by BamHI ribotyping and pulsed-field gel electrophoresis (PFGE) of XbaI digests of total deoxyribonucleic acid (DNA). Twenty-four patients had septicaemic melioidosis with a mortality of 70%; mortality in the non-septicaemic disease was 16%. Five ribotype patterns were identified, 2 of which accounted for 90% of all isolates. PFGE revealed a number of different strains within these ribotypes, but some pairs of isolates from unrelated cases gave closely similar DNA profiles. These results are in agreement with Australian studies which showed a high prevalence of a few ribotypes of B. pseudomallei which are further divisible by genotyping, in areas where melioidosis is endemic.

Wuthiekanun V, Smith MD, Dance DA, Walsh AL, Pitt TL, White NJ. 1996. Biochemical characteristics of clinical and environmental isolates of Burkholderia pseudomallei. J Med Microbiol, 45 (6), pp. 408-412. | Show Abstract | Read more

The biochemical characteristics of 213 isolates of Burkholderia pseudomallei from patients with melioidosis and 140 isolates from the soil in central and northeastern Thailand were compared. Whereas the biochemical profiles of all the clinical isolates were similar, all soil isolates from the central area and 25% of isolates from northeastern Thailand comprised a different phenotype. This was characterised by the ability to assimilate L-arabinose (100%), adonitol (100%), 5-keto-gluconate (90%) and D-xylose (84%), but failure to assimilate dulcitol (0%), erythritol (0%) and trehalose (10%). Compared with clinical isolates, these organisms had similar antibiotic susceptibility profiles and were also recognised by a specific polyclonal antibody against B. pseudomallei. As melioidosis is rare in central Thailand, but common in the northeast, this raises the possibility that this biochemical phenotype may be less virulent, or may even represent a different species.

Santanirand P, Harley V, Dance DAB, Bancroft GJ. 1996. Role of interferon-gamma and other cytokines in melioidosis IMMUNOLOGY, 89 pp. OY420-OY420.

Kang G, Rajan DP, Ramakrishna BS, Aucken HM, Dance DA. 1996. Melioidosis in India. Lancet, 347 (9014), pp. 1565-1566. | Read more

Dance DAB. 1996. Plague and melioidosis CURRENT OPINION IN INFECTIOUS DISEASES, 9 (2), pp. 120-125. | Show Abstract | Read more

Plague and melioidosis are both potentially fatal bacterial infections found mainly in the tropics. Up to 2000 cases of plague are reported to the World Health Organization each year, although this is probably inaccurate. Melioidosis is known to be prevalent in north-east Thailand and northern Australia, but we have little idea of its true worldwide importance. Molecular techniques are improving our understanding of the pathogenesis and epidemiology of both diseases and providing new, rapid diagnostic tests. Clinical trials are helping to define the role of new β-lactams such as ceftazidime and co-amoxiclav in the management of melioidosis, but the treatment of plague has not advanced since the end of the Vietnam War.

Viravan C, Dance DA, Ariyarit C, Looareesuwan S, Wattanagoon Y, Davis TM, Wuthiekanun V, Tantivanich S, Angus BJ, White NJ. 1996. A prospective clinical and bacteriologic study of inguinal buboes in Thai men. Clin Infect Dis, 22 (2), pp. 233-239. | Show Abstract | Read more

One-hundred thirteen men (mean age, 23 years) who presented with inguinal buboes to a government-operated hospital for sexually transmitted diseases (STDs) in Bangkok were studied between February 1987 and February 1989. The median duration of preceding symptoms was 7 days (range, 1-62 days). The majority of patients (74; 65%) had received treatment previously; 31 (27%) were febrile, 13 (12%) had extrainguinal lymphadenopathy, and 31 (27%) had concurrent active genital ulcers. There was no history of genital ulceration in 66 (58%) of the patients. Pus was obtained from 51 of the 110 buboes aspirated for culture; 21 (41%) of these cultures yielded Haemophilus ducreyi, and 2 (3.9%) were positive for Chlamydia trachomatis on immunofluorescence microscopy. Saline (1 mL) was injected and reaspirated from the buboes of 35 of the other 59 patients; 3 buboes yielded H. ducreyi and 9 were positive for C. trachomatis. All cultures for other aerobic and anaerobic bacteria and viruses in intact buboes were negative. Syphilis serology was positive in only one case. Patients attending STD clinics in this region who have large, fluctuant, edematous inguinal buboes containing pus should receive presumptive treatment for chancroid. If there is no pus, then the bubo is more likely to be caused by lymphogranuloma venereum.

Walsh AL, Smith MD, Wuthiekanun V, Suputtamongkol Y, Chaowagul W, Dance DA, Angus B, White NJ. 1995. Prognostic significance of quantitative bacteremia in septicemic melioidosis. Clin Infect Dis, 21 (6), pp. 1498-1500. | Show Abstract | Read more

Pour-plate blood cultures were performed for 418 adult patients with suspected septicemic melioidosis in order to determine the relationship between quantitative bacterial counts in blood and mortality. Of 108 patients whose hemocultures yielded Burkholderia pseudomallei, 53% had < 10 cfu/mL and 24% had > 100 cfu/mL. High blood bacterial counts were more common than reported previously with regard to other gram-negative septicemias and were significantly associated with the development of hypotension (P = .008) and a fatal outcome (P = .0001). The overall mortality was 63% (95% CI, 53%-72%); however, counts of < or = 1 cfu/mL were associated with a mortality of 42% (95% CI, 28%-58%), compared with 96% (95% CI, 80%-100%) with counts of > 100 cfu/mL. Heavy bacteremia (> 50 cfu/mL) is common in septicemic melioidosis and is usually fatal.

Rajchanuvong A, Chaowagul W, Suputtamongkol Y, Smith MD, Dance DA, White NJ. 1995. A prospective comparison of co-amoxiclav and the combination of chloramphenicol, doxycycline, and co-trimoxazole for the oral maintenance treatment of melioidosis. Trans R Soc Trop Med Hyg, 89 (5), pp. 546-549. | Show Abstract | Read more

An open randomized comparison of the oral 'conventional' regimen (combination of chloramphenicol, cotrimoxazole and doxycycline) and co-amoxiclav for the maintenance treatment of melioidosis was conducted in Ubon Ratchatani, north-eastern Thailand, between 1989 and 1992. The total antibiotic treatment duration was 20 weeks. Of 101 patients followed, 10 (10%; 95% confidence interval [CI] 4.9-17.5%) subsequently relapsed: 2 of 52 patients (4%) in the oral 'conventional' group, and 8 of 49 patients (16%) receiving oral co-amoxiclav. This compares with a relapse rate of 23% in our previous study of 8 weeks' total therapy. Only 50% of patients complied with the 20 weeks' treatment regimen and poor compliance proved the most significant risk factor for subsequent relapse (relative risk [RR] 4.9, 95% CI 1.2-20.3). Neither the presence of known underlying disease nor choice of initial parenteral treatment was significantly associated with a higher risk of relapse. Co-amoxiclav is safer and better tolerated, but may be less effective (RR of relapse 0.4, 95% CI 0.2-1.2) than the oral 'conventional' regimen. The minimum duration of total treatment with either regimen should be 12-20 weeks, depending on clinical progress.

Dance DA, Sanders D, Pitt TL, Speller DC. 1995. Burkholderia pseudomallei and Indian plague-like illness. Lancet, 346 (8979), pp. 904-905. | Read more

Wuthiekanun V, Smith MD, Dance DA, White NJ. 1995. Isolation of Pseudomonas pseudomallei from soil in north-eastern Thailand. Trans R Soc Trop Med Hyg, 89 (1), pp. 41-43. | Show Abstract | Read more

In order to optimize the recovery from soil of Pseudomonas pseudomallei, the cause of melioidosis, 3 selective broths were compared. A basal salt solution containing L-threonine (TBSS) performed significantly better than trypticase soy broth containing crystal violet and colistin 50 mg/L (CVC50), both in isolation rate and suppression of overgrowth of other organisms, but the addition of colistin to TBSS gave the best results overall. In a survey in north-eastern Thailand, P. pseudomallei was recovered from 114 (68%) of the 167 sites tested. A detailed study of a single rice farm showed that the isolation rate increased with depth of soil sample, and P. pseudomallei could still be isolated during the dry season, although only from moist soil in areas where other crops were cultivated and around the water source.

Suputtamongkol Y, Rajchanuwong A, Chaowagul W, Dance DA, Smith MD, Wuthiekanun V, Walsh AL, Pukrittayakamee S, White NJ. 1994. Ceftazidime vs. amoxicillin/clavulanate in the treatment of severe melioidosis. Clin Infect Dis, 19 (5), pp. 846-853. | Show Abstract | Read more

An open, paired, randomized, controlled trial of high-dose parenteral ceftazidime (120 mg/[kg.d]) vs. amoxicillin/clavulanate (160 mg/[kg.d]) for the treatment of severe melioidosis was conducted in Ubon Ratchatani in northeastern Thailand. Of 379 patients enrolled in the study, 212 (56%) had culture-proven melioidosis; 106 patients were in each treatment group. The overall mortality rate (47%) was similar for both treatment groups. However, 4 of 75 surviving patients in the ceftazidime group compared with 16 of 69 surviving patients in the amoxicillin/clavulanate group were switched to the alternate regimen because of an unsatisfactory clinical response after > or = 72 hours of treatment (P = .004). The overall therapeutic failure rate (i.e., treatment failure or death due to uncontrolled melioidosis) was significantly higher for the amoxicillin/clavulanate group than for the ceftazidime group (P = .02). Clinical and bacteriologic responses for successfully treated patients were similar in both groups, and both treatments were well tolerated. Parenteral amoxicillin/clavulanate is a safe and effective initial treatment, but parenteral ceftazidime remains the treatment of choice for severe melioidosis.

Desakorn V, Smith MD, Wuthiekanun V, Dance DA, Aucken H, Suntharasamai P, Rajchanuwong A, White NJ. 1994. Detection of Pseudomonas pseudomallei antigen in urine for the diagnosis of melioidosis. Am J Trop Med Hyg, 51 (5), pp. 627-633. | Show Abstract | Read more

An enzyme-linked immunosorbent assay using a fluorescein isothiocyanate (FITC)-anti-FITC amplification system, has been developed to detect Pseudomonas pseudomallei antigen in urine. The assay was evaluated in 135 patients with acute melioidosis, 194 hospitalized patients with other disorders, and 40 healthy controls. Antigen was detected in the urine of 123 (91%) patients with melioidosis. Urinary antigen was found in 85 (96%) of 89 patients with septicemic melioidosis, all six patients with P. pseudomallei urinary tract infection, and 32 (80%) of 40 patients with other localized infections. Antigen was not detected in the urine of 40 healthy individuals, but the urine of 16 (8%) of 194 hospitalized patients with diagnoses other than melioidosis gave a positive result. Of the false-positive results, 13 of 16 were associated with bacteriuria > or = 10(4) colony-forming units/ml. At a cutoff titer of 1:10, the sensitivity and specificity of the test were 81% and 96%, respectively. Enzyme immunoassay detection of urinary antigen is a valuable and rapid laboratory test for the early diagnosis of acute melioidosis.

Suputtamongkol Y, Hall AJ, Dance DA, Chaowagul W, Rajchanuvong A, Smith MD, White NJ. 1994. The epidemiology of melioidosis in Ubon Ratchatani, northeast Thailand. Int J Epidemiol, 23 (5), pp. 1082-1090. | Show Abstract | Read more

BACKGROUND: Melioidosis, or infection with Pseudomonas pseudomallei is an important cause of morbidity and mortality in South East Asia and Northern Australia. The epidemiology of melioidosis in Ubon Ratchatani, Northeast Thailand was studied over a 5-year period from 1987 to 1991. METHODS: Rates and, when possible, the risks of developing melioidosis were calculated. The numerator was the number of culture-proven cases of melioidosis seen in the 1000-bed referral hospital of the province. The denominators were obtained from the population census, a survey of Health, Welfare and Use of Traditional Medicine, and the North Eastern Meterological Centre, Thailand. RESULTS: The average incidence of human melioidosis was 4.4 (95% confidence interval [CI]: 3.8-5.0) per 100,000. The disease affected all ages with the highest incidence in 40-60 years olds. Melioidosis was 1.4 (95% CI: 0.4-5.3) times more common in males than females. The disease showed a significant seasonal variation in incidence, and a strong linear correlation with rainfall (r = 0.7, 95% CI: 0.5-0.9) Adults exposed to soil and water in their work (most were rice farmers) had an increased risk of melioidosis (in the 40-59 year age group, relative risk = 4.1, 95% CI: 2.4-6.9). Most adult patients had an underlying disease (mainly diabetes mellitus) predisposing them to this infection. CONCLUSION: Melioidosis may result from either acute exposure to the organism in the soil and water, or 're-activation' of an asymptomatic childhood infection (by an unidentified possibly infective seasonal cofactor). The results from this analysis are consistent with both hypotheses. Further epidemiological studies are needed to identify risk factors so that optimal strategies for control of melioidosis may be developed.

Trakulsomboon S, Pitt TL, Dance DA. 1994. Molecular typing of Pseudomonas pseudomallei from imported primates in Britain. Vet Rec, 135 (3), pp. 65-66. | Read more

Bryan LE, Wong S, Woods DE, Dance DA, Chaowagul W. 1994. Passive protection of diabetic rats with antisera specific for the polysaccharide portion of the lipopolysaccharide isolated from Pseudomonas pseudomallei. Can J Infect Dis, 5 (4), pp. 170-178. | Show Abstract | Read more

Polyclonal and monoclonal antisera raised to tetanus toxoid-conjugated polysaccharide of lipopolysaccharide (lps) and purified lps of Pseudomonas pseudomallei that reacted with a collection of 41 strains of this bacterium from 23 patients are described. The common antigen recognized by these sera was within the polysaccharide component of the lps of the cells. The sera were specific for P pseudomallei in that none of 37 strains of other bacteria, including 20 Gram-negative and three Gram-positive species, were recognized, although cross-reaction occurred using the anticonjugate serum with some strains of Pseudomonas cepacia serotype A, a closely related bacterium. Passive protection studies using a diabetic rat model of P pseudomallei infection showed that partially purified rabbit polyclonal and mouse monoclonal antisera were protective when the median lethal dose was raised by four to five orders of magnitude. The wide distribution of the polysaccharide antigen among isolates of P pseudomallei used in this study and the protective role of antibody to the conjugated polysaccharide antigen suggest potential as a vaccine.

Batchelor BI, Paul J, Trakulsomboon S, Mgongo M, Dance DA. 1994. Melioidosis survey in Kenya. Trans R Soc Trop Med Hyg, 88 (2), pp. 181. | Read more

Chaowagul W, Suputtamongkol Y, Dance DA, Rajchanuvong A, Pattara-arechachai J, White NJ. 1993. Relapse in melioidosis: incidence and risk factors. J Infect Dis, 168 (5), pp. 1181-1185. | Show Abstract | Read more

From 1986 to 1991, 602 patients with melioidosis were seen in Sappasitprasong Hospital, Ubon Ratchatani, Thailand. The in-hospital mortality was 42%. Of 118 adult patients followed long-term, 27 (23%) had culture-proven relapses of melioidosis (3 relapsed twice), a relapse rate of 15% (95% confidence interval [CI], 11-22) per year. The median time from discharge to relapse was 21 weeks (range, 1-290). In 44% of patients, relapses included septicemia, and 27% died. Patients with severe disease (multiple foci of infection or septicemia) relapsed 4.7 times (95% CI, 1.6-14.1) more frequently than patients with localized melioidosis. Underlying disease was not a risk factor, but initial parenteral treatment with ceftazidime reduced the risk of relapse 2-fold (95% CI, 1.1-3.4). Relapses were 3.3 (95% CI, 1.4-9.0) times more frequent following short-course (< or = 8 weeks) oral coamoxiclav than after the oral combination regimen of chloramphenicol, doxycycline, and cotrimoxazole. Longer oral treatment with either reduced relapse 1.6-fold (95% CI, 1.2-1.9). The optimum choice and duration of antibiotic treatment to prevent relapse in melioidosis remain to be determined.

Desmarchelier PM, Dance DA, Chaowagul W, Suputtamongkol Y, White NJ, Pitt TL. 1993. Relationships among Pseudomonas pseudomallei isolates from patients with recurrent melioidosis. J Clin Microbiol, 31 (6), pp. 1592-1596. | Show Abstract

Patients with melioidosis may present with recurrent infections after clinical resolution of their primary illness. Because there has been no satisfactory typing scheme for Pseudomonas pseudomallei, recrudescence could not be distinguished from reinfection. We determined the strain identity of primary and relapse isolates of P. pseudomallei from 25 patients with culture-proven melioidosis to answer whether secondary infections were due to the initial infecting strain or to the acquisition of a new strain. Fifty-four isolates were compared by the patterns of BamHI restriction digests produced after hybridization with a cDNA copy of Escherichia coli rRNA. Twenty-three patients had primary and relapse isolates with identical or highly similar ribotype patterns. The patterns of isolates from two patients were different; the primary and relapse isolates differed by a single fragment for one, and the other had identical primary and first-relapse isolates while the second-relapse isolate was markedly different. The results indicated that recurrent infection probably resulted from endogenous relapse in most of the melioidosis patients studied, although reinfection from an exogenous source was also possible in two cases.

Van Phung L, Quynh HT, Yabuuchi E, Dance DA. 1993. Pilot study of exposure to Pseudomonas pseudomallei in northern Vietnam. Trans R Soc Trop Med Hyg, 87 (4), pp. 416. | Read more

Kanaphun P, Thirawattanasuk N, Suputtamongkol Y, Naigowit P, Dance DA, Smith MD, White NJ. 1993. Serology and carriage of Pseudomonas pseudomallei: a prospective study in 1000 hospitalized children in northeast Thailand. J Infect Dis, 167 (1), pp. 230-233. | Show Abstract | Read more

Throat swab cultures and indirect hemagglutination assay (IHA) for Pseudomonas pseudomallei were done in 1000 randomly selected children at a large hospital in northeast Thailand. During 18 months, 17 children with melioidosis were admitted (0.46% of pediatric admissions excluding neonates born in the hospital). Throat swab was positive for P. pseudomallei in 8 of these but in none of 1000 control children. IHA seroprevalence rose at a conversion rate of 24% per year, from 12% in those 1-6 months old to a plateau at approximately 80% after age 4 years. No control child < 4 had an IHA titer > 1:160. The median titer in children with melioidosis was 1:80 (range, negative [in3]-1:5120). Specificity of IHA declined with age, but high titers (> or = 1:640) remained diagnostically useful. Thus, throat carriage of P. pseudomallei indicates active melioidosis. There is no evidence for an asymptomatic carrier state in children. Environmental exposure to P. pseudomallei in endemic areas begins when the child becomes mobile.

Dance DA, King C, Aucken H, Knott CD, West PG, Pitt TL. 1992. An outbreak of melioidosis in imported primates in Britain. Vet Rec, 130 (24), pp. 525-529. | Show Abstract | Read more

An outbreak of melioidosis, a bacterial infection caused by Pseudomonas pseudomallei, was identified in a batch of feral cynomolgus monkeys (Macaca fascicularis) imported to Britain from the Philippines. Thirteen confirmed or possible cases occurred among a batch of 50 animals. Subsequent investigations revealed that the infection was uncommon among imported primates from a variety of sources, although three other cases were identified in monkeys imported from Indonesia. The majority of the affected monkeys had splenic abscesses, and hepatic abscesses and infections of the soft tissues and skin were also frequently observed. Most of the infected animals had no clinical signs despite extensive abscesses, and the presence of infection was only suspected when they were shown to have serum antibodies to P pseudomallei by an enzyme-linked immunosorbent assay. Although there was no evidence of cross infection of other animals or human handlers, this outbreak is a reminder of the dangers of working with wild-caught primates and the potential for the establishment of environmental foci of melioidosis.

Suputtamongkol Y, Kwiatkowski D, Dance DA, Chaowagul W, White NJ. 1992. Tumor necrosis factor in septicemic melioidosis. J Infect Dis, 165 (3), pp. 561-564. | Show Abstract | Read more

Plasma concentrations of the cytokine tumor necrosis factor (TNF) were measured serially in 91 patients suspected of having septicemic melioidosis. This was confirmed in 55. TNF was detectable in admission plasma (TNF0) in 3 of 15 survivors of septicemic melioidosis and 21 of 26 fatal cases (P less than .001). The median (range) TNF0 concentration in melioidosis patients who died was 96 (1-4774) pg/ml, and the median time to death was 25 (5-672) h. TNF0 was inversely correlated with the lowest mean arterial pressure in the succeeding 12 h (Spearman's rank correlation coefficient = .67, 2P less than .001). Three patterns of TNF plasma concentrations were evident: relatively constant values between 100 and 500 pg/ml (n = 7), high admission concentrations (greater than 1000 pg/ml) associated with early death (n = 4), and an apparent pulse release after treatment, with peak values greater than 1000 pg/ml, which then declined with a mean (SD) apparent half-time of 131 (50) min (n = 8). Further studies are necessary to determine whether TNF contributes to lethality in melioidosis.

Vatcharapreechasakul T, Suputtamongkol Y, Dance DA, Chaowagul W, White NJ. 1992. Pseudomonas pseudomallei liver abscesses: a clinical, laboratory, and ultrasonographic study. Clin Infect Dis, 14 (2), pp. 412-417. | Show Abstract | Read more

Ultrasonography revealed evidence of liver abscess in 126 patients who were admitted to one hospital in northeastern Thailand over a 3-year period. There were 50 cases for which a pyogenic bacterial etiology was confirmed; 34 cases (group 1) were caused by Pseudomonas pseudomallei (nine patients died) and 16 cases (group 2) were caused by other bacteria (two patients died). Melioidosis was associated with anemia and underlying diabetes or renal disease; right-upper-quadrant pain and jaundice were more common in group 2 (P less than .05). Blood cultures were positive for bacteria in 68% of group 1 and 50% of group 2. Chest radiographs revealed abnormalities in 17 of 30 group 1 patients and 6 of 12 group 2 patients. The radiographic appearances of a blood-borne pneumonia suggested melioidosis. The serum indirect hemagglutination assay for antibodies to P. pseudomallei was of limited value in differentiating the two types of abscesses. Multiple hypoechoic areas on ultrasonography were significantly associated with melioidosis (P less than .01); associated splenic abscess occurred in 19 group 1 patients but only one group 2 patient (2-107, 95% confidence interval; odds ratio, 19). In an area where P. pseudomallei is endemic, these characteristic ultrasonographic findings should prompt immediate treatment for melioidosis.

Pitt TL, Aucken H, Dance DA. 1992. Homogeneity of lipopolysaccharide antigens in Pseudomonas pseudomallei. J Infect, 25 (2), pp. 139-146. | Show Abstract | Read more

An antiserum raised against a single strain of Pseudomonas pseudomallei reacted equally in a whole cell agglutination test, an indirect haemagglutination (IHA) test and an ELISA with a panel of 12 strains of the species which had been isolated from human beings and animals in various parts of the Far East and Australia between 1923 and 1990. Absorption of the serum with either of two strains removed all reactivity of the serum with other strains. Phenol-water extracted lipopolysaccharide (LPS) from a single strain blocked the reactivity of the serum with red cells sensitised with crude extracts of any of the panel of strains, thereby suggesting that the 'common' antigen was LPS. This antigen was not detected in other Pseudomonas species with the exception of Pseudomonas mallei. Protease K-digested extracts of the 12 strains gave highly similar silver-stained LPS banding patterns in gel electrophoresis. Furthermore, immunoblots of LPS with either rabbit or a patient's serum showed identical ladder profiles for each strain. The results suggest that the LPS antigen is highly conserved throughout P. pseudomallei and that this antigen is detected by the IHA test.

Dance DA, Smith MD, Wuthiekanun V, Walsh M, White NJ. 1992. Melioidosis and laboratory safety. J Hosp Infect, 22 (4), pp. 333-334. | Read more

Dance D, Richens JE, Ho M, Acharya G, Pokhrel B, Tuladhar NR. 1991. Blood and bone marrow cultures in enteric fever. J Clin Pathol, 44 (12), pp. 1038. | Read more

Suputtamongkol Y, Dance DA, Chaowagul W, Wattanagoon Y, Wuthiekanun V, White NJ. 1991. Amoxycillin-clavulanic acid treatment of melioidosis. Trans R Soc Trop Med Hyg, 85 (5), pp. 672-675. | Show Abstract | Read more

Melioidosis is a serious infection with high acute mortality, and a high rate of relapse despite protracted antimicrobial treatment. The current recommended conventional oral treatment regimen is a 4-drug combination of high-dose chloramphenicol, doxycycline and trimethoprim-sulphamethoxazole given for between 6 weeks and 6 months. We have evaluated prospectively the use of amoxycillin-clavulanic acid, to which Pseudomonas pseudomallei is consistently sensitive in vitro, for the oral maintenance treatment of melioidosis. Amoxycillin-clavulanic acid was used either as sole treatment of localized disease, or as maintenance therapy following either parenteral ceftazidime or the conventional 4-drug regime; 20 patients with localized infections and 26 with septicaemic melioidosis received a median of 7.5 (2-12) weeks treatment. After a mean follow-up period of 6 months (range 1-19), 31 patients (67%) remain free of disease. The drug was well tolerated. Three patients had fatal relapses, one other died suddenly at home, and another died from underlying promyelocytic leukaemia. The remaining 10 relapses were treated successfully. Resistance developed in one case. Amoxycillin-clavulanic acid is a safe alternative to the conventional 4-drug antimicrobial combination for the oral treatment of melioidosis. It may be of particular value in children, pregnant women, and in infections with Ps. pseudomallei resistant to the potentially toxic conventional regimen, but the optimum dose and duration of therapy need to be established.

Lockett AE, Dance DA, Mabey DC, Drasar BS. 1991. Serum-free media for isolation of Haemophilus ducreyi. Lancet, 338 (8762), pp. 326. | Read more

Dance DA, Wuthiekanun V, Chaowagul W, Suputtamongkol Y, White NJ. 1991. Development of resistance to ceftazidime and co-amoxiclav in Pseudomonas pseudomallei. J Antimicrob Chemother, 28 (2), pp. 321-324. | Read more

Godfrey AJ, Wong S, Dance DA, Chaowagul W, Bryan LE. 1991. Pseudomonas pseudomallei resistance to beta-lactam antibiotics due to alterations in the chromosomally encoded beta-lactamase. Antimicrob Agents Chemother, 35 (8), pp. 1635-1640. | Show Abstract | Read more

Pseudomonas pseudomallei, the causative agent of melioidosis, is generally susceptible to some of the newer extended-spectrum cephalosporins or to combinations of a beta-lactam and clavulanic acid, a beta-lactamase inhibitor. Resistance to these agents may, however, emerge during treatment. We report on alterations in the chromosomal beta-lactamase associated with the development of resistance. Three resistance patterns resulted from three different mechanisms in the strains investigated. Derepression of the chromosomal enzyme resulted in a general increase in the MICs of all of the beta-lactams tested. The second mechanism observed was an insensitivity to inhibition of the beta-lactamase by clavulanic acid. In this case, the level of susceptibility to beta-lactams as independent entities remained unchanged. The final "resistance" pattern occurred in a patient treated with ceftazidime and resulted in a beta-lactamase that was capable of hydrolyzing this antibiotic at detectable levels, but with reduced efficacy against other beta-lactams. The net result was a strain that was generally susceptible to all of the beta-lactams tested except ceftazidime. In all cases, the level of susceptibility to antibiotics other than beta-lactams remained unchanged. Such variability found within one genus over a relatively short time course suggests that treatment of infections caused by this organism should be carefully monitored to detect susceptibility alterations to the chosen therapy.

Brown AE, Dance DA, Suputtamongkol Y, Chaowagul W, Kongchareon S, Webster HK, White NJ. 1991. Immune cell activation in melioidosis: increased serum levels of interferon-gamma and soluble interleukin-2 receptors without change in soluble CD8 protein. J Infect Dis, 163 (5), pp. 1145-1148. | Show Abstract | Read more

To evaluate immune cell activation in patients with melioidosis, serum samples were assayed for interferon-gamma (IFN-gamma), soluble interleukin-2 receptors (sIL-2R), and soluble CD8 protein (sCD8). Forty patients with sepsis (23 fatal cases, 17 survivors) and 13 with localized disease were studied during acute illness; 12 additional patients were studied after discharge while on maintenance antimicrobial therapy. Serum concentrations of IFN-gamma and sIL-2R were greatly elevated, but sCD8 concentrations were not. These levels increased with disease severity and were associated with fatal outcomes. Macrophage activation by high concentrations of the cytokine IFN-gamma may contribute to pathophysiology and death in septicemic patients. Both IFN-gamma and sIL-2R seem to be predictive of outcome in patients with severe melioidosis and may prove useful in detection of relapse.

Siripanthong S, Teerapantuwat S, Prugsanusak W, Suputtamongkol Y, Viriyasithavat P, Chaowagul W, Dance DA, White NJ. 1991. Corneal ulcer caused by Pseudomonas pseudomallei: report of three cases. Rev Infect Dis, 13 (2), pp. 335-337. | Show Abstract

We report three cases of corneal ulcer caused by Pseudomonas pseudomallei. In all cases corneal trauma preceded the development of extensive ulcers, subconjunctival abscesses, and hypopyon. Treatment for a total of 8 weeks with topical and/or parenteral ceftazidime followed by amoxicillin-clavulanic acid produced resolution of infection in each case.

Smith CJ, Jones M, Dance DA, Chaowagul W, White NJ. 1991. Diagnosis of melioidosis by means of an ELISA detecting antibodies toPseudomonas pseudomallei exotoxin. Preliminary assay evaluation. World J Microbiol Biotechnol, 7 (1), pp. 29-36. | Show Abstract | Read more

An ELISA system for the detection of human antibodies toPseudomonas pseudomallei exotoxin is described. Analysis of control sera and sera from patients with culture-positive melioidosis showed that both IgG and IgM antibodies to exotoxin were detectable in patients with melioidosis. This implies that the exotoxin is producedin vivo byP. pseudomallei, and may be involved in the pathogenesis of melioidosis. Furthermore, these rapid and simple assays may prove to be useful for the serodiagnosis of the disease.

Dance DA. 1991. Pseudomonas pseudomallei: danger in the paddy fields. Trans R Soc Trop Med Hyg, 85 (1), pp. 1-3. | Read more

Dance DA. 1991. Melioidosis: the tip of the iceberg? Clin Microbiol Rev, 4 (1), pp. 52-60. | Show Abstract | Read more

For nearly 80 years clinical melioidosis has been considered a rare disease. This bacterial infection is caused by Pseudomonas pseudomallei, a saprophyte found in soil and surface water of endemic areas. Consequently, those who have most contact with soil, the rural poor, are likely to be at greatest risk of infection. Since the diversity of clinical manifestations necessitates the isolation and identification of the causative organism for a definitive diagnosis of melioidosis and the population at greatest risk within endemic areas rarely have access to an appropriate level of health care, the disease has probably been underrecognized. Melioidosis is now known to be an important cause of human morbidity and mortality in Thailand, and this may be true throughout Southeast Asia, which is usually regarded as the main endemic area for the disease. In Australia, melioidosis causes a smaller number of human infections, while disease among livestock has important economic and possible public health implications. Sporadic reports of the infection indicate its presence in several other tropical regions: in the Indian subcontinent, Africa, and Central and South America. Clinical melioidosis may be highly prevalent in these areas, but underdiagnosed as a result of a lack of awareness of the clinical and microbiological features of the disease, or simply because of a lack of health care facilities. Furthermore, during the last two decades the importation and transmission of melioidosis within nontropical zones have been documented. The causative organism is not difficult to grow, and modern antibiotics have improved disease prognosis. Further studies are needed to determine the true worldwide distribution and prevalence of melioidosis so that improved therapeutic and preventive measures can be developed and applied.

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Dance DAB. 1990. Melioidosis Reviews in Medical Microbiology, 1 (3), pp. 143-150. | Show Abstract

Regarded for nearly 80 years as a rare disease, melioidosis is emerging as an important cause of morbidity and mortality in North East Thailand, and is probably underdiagnosed elsewhere. Infection with environmental Pseudomonas pseudomallei occurs during the rainy season, but the mode of acquisition is usually unclear, and the infection may remain latent for several years. Much remains to be learned about the interactions between host defence mechanisms and bacterial virulence factors in the disease. Fulminant septicaemia in immunocompromised patients is the most frequent clinical manifestation, although serological surveys suggest that self-limiting infections are widespread in the normal population. Since diagnosis still depends on isolation of the causative organism, rapid and improved serodiagnostic tests are urgently needed. New beta-lactam drugs, such as ceftazidime, have significantly reduced the mortality of the disease, although the emergence of resistance and late relapses of infection present challenging therapeutic problems.

Dance DA, White NJ, Suputtamongkol Y, Chaowagul W. 1990. Pseudomonas pseudomallei and sudden unexplained death in Thai construction workers. Lancet, 336 (8725), pp. 1257-1258. | Read more

Wuthiekanun V, Dance DA, Wattanagoon Y, Supputtamongkol Y, Chaowagul W, White NJ. 1990. The use of selective media for the isolation of Pseudomonas pseudomallei in clinical practice. J Med Microbiol, 33 (2), pp. 121-126. | Show Abstract | Read more

Ashdown's selective-differential agar medium, with or without preenrichment in selective broth, was evaluated for the isolation of Pseudomonas pseudomallei from 1972 clinical specimens obtained from 643 subjects in Northeast Thailand; 226 patients proved to have meliodosis. The use of Ashdown's medium significantly increased the frequency of recovery of P. pseudomallei from sites or specimens with an extensive normal flora (throat, rectum, wounds and sputum) as compared to the recovery on blood and MacConkey agars (p less than 0.01). The isolation frequency from throat, rectal and wound swabs was further increased by the use of the broth pre-enrichment. The colonial morphology of P. pseudomallei on Ashdown's medium was sufficiently characteristic to allow presumptive identification. With the use of these selective media it was possible to culture P. pseudomallei from throat swabs taken from 87% of the patients from whom the organism could also be isolated from corresponding tracheal aspirates or sputum specimens. P. pseudomallei was isolated from rectal swabs taken from 51 patients, the first time that faecal excretion of the organism has been demonstrated in man. The diagnosis of melioidosis would not have been confirmed bacteriologically in eight patients (3.5%) without the use of the selective media. It is suggested that, in areas endemic for melioidosis, all sputum specimens should be cultured on selective media, such as Ashdown's. For the investigation of clinically suspected cases of melioidosis, and for follow-up during treatment of the disease, the use of broth pre-enrichment is recommended for specimens obtained from sites with an extensive normal flora.

Dance DA, Suputtamongkol Y, Chaowagul W, White NJ. 1990. Prophylaxis for contacts of melioidosis. J Infect, 21 (2), pp. 222-223. | Read more

Wuthiekanun V, Dance D, Chaowagul W, Suputtamongkol Y, Wattanagoon Y, White N. 1990. Blood culture techniques for the diagnosis of melioidosis. Eur J Clin Microbiol Infect Dis, 9 (9), pp. 654-658. | Show Abstract | Read more

The effects of variations in laboratory technique on the speed and sensitivity of isolation of Pseudomonas pseudomallei from blood were evaluated prospectively. Pseudomonas pseudomallei was isolated from 154 of 546 cultures from 325 patients with suspected or confirmed melioidosis. Subcultures after 12 to 24 and 36 to 48 hours of incubation were positive in 52.3% and 80.8% respectively. The yields from 20 ml (blood to broth ratio 1:4) and 50 ml (blood to broth ratio 1:10) brain heart infusion broth bottles were equivalent in patients not receiving treatment for melioidosis. During therapy, the 50 ml bottles grew Pseudomonas pseudomallei significantly faster than the 20 ml bottles (p less than 0.01), and gave a higher overall yield for cultures processed in antimicrobial removal devices (p less than 0.05). These devices themselves increased the speed of isolation of the organism from treated patients (p less than 0.01). In most cases, all bottles collected from a patient before treatment were positive, and a single 20 ml bottle had an estimated relative sensitivity of 85.7% (95% confidence interval 77.1-94.3%). Early subculture should be employed routinely for the laboratory diagnosis of septicaemic melioidosis. However, blood culture techniques do not need to be sophisticated. Culture of 5 ml blood in 20 ml broth is a simple and sensitive procedure suitable for regions where melioidosis is currently under-diagnosed.

Brown AE, Dance DA, Chaowagul W, Webster HK, White NJ. 1990. Activation of cellular immune responses in melioidosis patients as assessed by urinary neopterin. Trans R Soc Trop Med Hyg, 84 (4), pp. 583-584. | Read more

Dance DA, White NJ, Suputtamongkol Y, Wattanagoon Y, Wuthiekanun V, Chaowagul W. 1990. The use of bone marrow culture for the diagnosis of melioidosis. Trans R Soc Trop Med Hyg, 84 (4), pp. 585-587. | Show Abstract | Read more

We have evaluated prospectively the contribution of bone marrow culture to the diagnosis of melioidosis. Bone marrow (BMC) and blood cultures (BC) were collected concurrently from 105 patients with suspected acute, severe melioidosis. 67 patients were subsequently proved to have the disease whilst other significant organisms were isolated from these specimens in 5 cases. Overall, 67.2% of BC and 64.2% of BMC from melioidosis patients grew Pseudomonas pseudomallei. Time to positivity did not differ significantly in paired BC and BMC specimens. These results do not support the routine use of BMC in the diagnosis of acute, severe melioidosis. In one patient with pulmonary melioidosis, however, blood cultures were repeatedly negative, whilst bone marrow grew P. pseudomallei, and this preceded the development of a distant focus of infection. This suggests that culture of bone-marrow may be of value in certain blood culture-negative patients with melioidosis.

Karim QN, Finn GY, Easmon CS, Dangor Y, Dance DA, Ngeow YF, Ballard RC. 1989. Rapid detection of Haemophilus ducreyi in clinical and experimental infections using monoclonal antibody: a preliminary evaluation. Genitourin Med, 65 (6), pp. 361-365. | Show Abstract

A monoclonal antibody raised against Haemophilus ducreyi was tested for its sensitivity and specificity as an immunofluorescence (IF) reagent using simulated vaginal smears containing H. ducreyi, smears taken from skin lesions of mice infected with H. ducreyi and patients from South Africa, Thailand and Malaysia with clinically diagnosed chancroid. The IF test was more sensitive than culture or Gram staining in the simulated smears, theoretically detecting less than 4 organisms/sample. It detected H. ducreyi in 95% of the animal lesions compared with 14% detected by culture. Immunofluorescence testing identified over 90% of culture-positive cases of chancroid but also detected organisms in some culture-negative cases where clinical evidence for the diagnosis was strong. These results suggest that this antibody may provide a simple, rapid and sensitive means of detecting H. ducreyi in cases of chancroid.

Dance DA, Wuthiekanun V, Chaowagul W, White NJ. 1989. The activity of amoxycillin/clavulanic acid against Pseudomonas pseudomallei. J Antimicrob Chemother, 24 (6), pp. 1012-1014. | Read more

White NJ, Dance DA, Chaowagul W, Wattanagoon Y, Wuthiekanun V, Pitakwatchara N. 1989. Halving of mortality of severe melioidosis by ceftazidime. Lancet, 2 (8665), pp. 697-701. | Show Abstract | Read more

An open randomised trial was conducted to compare ceftazidime (120 mg/kg/day) with "conventional therapy" (chloramphenicol 100 mg/kg/day, doxycycline 4 mg/kg/day, trimethoprim 10 mg/kg/day, and sulphamethoxazole 50 mg/kg/day) in the treatment of severe melioidosis. A paired restricted sequential trial designed to detect a reduction in mortality from 80 to 40% in culture-positive patients surviving greater than 48 hours was stopped after 22 months. Of the 161 patients entered into the study, 65 had bacteriologically confirmed melioidosis and 54 of these were septicaemic. Ceftazidime treatment was associated with a 50% (95% CI 19-81%) lower overall mortality than conventional treatment (74% vs 37%; p = 0.009) and should now become the treatment of choice for severe melioidosis.

Dance DA, Wuthiekanun V, Chaowagul W, White NJ. 1989. The antimicrobial susceptibility of Pseudomonas pseudomallei. Emergence of resistance in vitro and during treatment. J Antimicrob Chemother, 24 (3), pp. 295-309. | Show Abstract | Read more

We have measured the in-vitro activity of 27 antimicrobials against 211 clinical and ten reference strains of Pseudomonas pseudomallei. Imipenem was the most active antibiotic tested, followed by piperacillin, doxycycline, amoxycillin/clavulanic acid, cefixime, cefetamet, azlocillin and ceftazidime, all of which had MICs of less than or equal to 2 mg/l for the majority of strains. The measured MICs were dependent on the media and inocula used, to an extent which varied with the antibiotic class under test; MICs of ureidopenicillins were particularly inoculum-dependent. The beta-lactams and ciprofloxacin were bactericidal, whereas the agents conventionally used to treat melioidosis (doxycycline, chloramphenicol, sulphamethoxazole and trimethoprim) had bacteriostatic activity only. Strains highly resistant to chloramphenicol (MIC greater than or equal to 256 mg/l) emerged during treatment in 7.1% of patients. These strains were fully virulent, and frequently showed cross-resistance to tetracyclines, sulphamethoxazole, trimethoprim and ciprofloxacin, with paradoxical increased susceptibility to beta-lactams and aminoglycosides. Similar resistance patterns were seen in mutants generated in vitro and two reference strains. One strain with isolated ceftazidime resistance, reversible by clavulanic acid, emerged during treatment. Several of the new beta-lactam antibiotics are of potential value in the therapy of P. pseudomallei infections. Patients should be carefully monitored for the emergence of antibiotic-resistant strains during treatment of melioidosis.

Dance DA, Wuthiekanun V, Chaowagul W, White NJ. 1989. Interactions in vitro between agents used to treat melioidosis. J Antimicrob Chemother, 24 (3), pp. 311-316. | Show Abstract | Read more

Combinations of antimicrobial agents are usually recommended for the treatment of melioidosis. In Thailand, the conventional treatment regimen for Pseudomonas pseudomallei infections is a combination of chloramphenicol, doxycycline and cotrimoxazole. We have consistently observed antagonism between these agents during routine disc susceptibility testing. Interactions between these antimicrobials were studied further by a chequerboard microdilution method, using five clinical isolates of P. pseudomallei. Both trimethoprim and sulphamethoxazole antagonised the bacteriostatic activity of chloramphenicol and doxycycline. The combination of trimethoprim and sulphamethoxazole was synergistic, but not bactericidal. Bacteriostatic drugs antagonised the bactericidal activity of ceftazidime, which is undergoing clinical trials in severe melioidosis. These findings may be of therapeutic relevance.

Dance DA, Wuthiekanun V, Naigowit P, White NJ. 1989. Identification of Pseudomonas pseudomallei in clinical practice: use of simple screening tests and API 20NE. J Clin Pathol, 42 (6), pp. 645-648. | Show Abstract | Read more

The API 20NE kit and a simple screening system involving Gram's stain, the oxidase reaction, colistin and gentamicin resistance, and colonial characteristics on a differential agar medium, were used to test 400 strains of Pseudomonas pseudomallei. The API kit identified 390 (97.5%) strains correctly on first testing and all but one of the remainder on second testing. Only one strain was initially misidentified (as Ps cepacia). The screening system was 100% accurate in identifying Ps pseudomallei. In non-endemic areas the API 20NE kit may be used to identify sporadic imported strains of Ps pseudomallei. Such kits may also help to delineate the geographical distribution of melioidosis. In endemic areas the screening tests described offer a cheap, simple, and accurate means of presumptively identifying Ps pseudomallei from clinical specimens.

Chaowagul W, White NJ, Dance DA, Wattanagoon Y, Naigowit P, Davis TM, Looareesuwan S, Pitakwatchara N. 1989. Melioidosis: a major cause of community-acquired septicemia in northeastern Thailand. J Infect Dis, 159 (5), pp. 890-899. | Show Abstract | Read more

In a prospective study of all patients with Pseudomonas pseudomallei infections admitted to a large provincial hospital in northeastern Thailand, 63 cases of septicemic melioidosis and 206 patients with other community-acquired septicemias were documented during a 1-y period. Apart from P. pseudomallei, the spectrum of bacteria isolated from blood cultures and the overall mortality (32%) were similar to those previously reported elsewhere. Death from septicemia was associated with failure to develop a leukocytosis or pyrexia over 38 degrees C, azotemia, hypoglycemia, and jaundice. Septicemic melioidosis presented mainly in the rainy season, occurred predominantly in rice farmers or their families, and was significantly associated with preexisting diabetes mellitus or renal failure (P = .03). Blood-borne pneumonia and visceral abscesses were common and the mortality was high (68%; P less than .001). The response to appropriate treatment was slow (median fever clearance time 5.5 d) and the median duration of hospital stay was 4 w. Septicemic melioidosis is a major cause of morbidity and mortality in northeast Thailand.

Dance DA, Davis TM, Wattanagoon Y, Chaowagul W, Saiphan P, Looareesuwan S, Wuthiekanun V, White NJ. 1989. Acute suppurative parotitis caused by Pseudomonas pseudomallei in children. J Infect Dis, 159 (4), pp. 654-660. | Show Abstract | Read more

During a prospective clinical study of melioidosis in northeast Thailand, suppurative parotitis was observed as a characteristic presentation in children. Parotitis constituted 6.3% of all culture-positive melioidosis and 38% of melioidosis in children. Nine cases are described. None had apparent predisposition to infection, although two patients developed rising mumps virus antibody titers, suggesting a possible relation between these conditions. Complications included abscess formation (nine), spontaneous rupture into the auditory canal (five), facial nerve palsy (two), and septicemia and osteomyelitis with septic arthritis (one each). All children initially responded to surgical drainage and appropriate antibiotic therapy. Pseudomonas pseudomallei parotitis should be considered in children from endemic areas with fever and facial swelling. It has a good prognosis with appropriate treatment. It may also prove to be a sensitive clinical indicator of the presence of melioidosis within a particular geographic area.

Dance DA, Wuthiekanun V, White NJ, Chaowagul W. 1988. Antibiotic resistance in Pseudomonas pseudomallei. Lancet, 1 (8592), pp. 994-995. | Read more

Struelens MJ, Mondol G, Bennish M, Dance DA. 1988. Melioidosis in Bangladesh: a case report. Trans R Soc Trop Med Hyg, 82 (5), pp. 777-778. | Read more

White NJ, Dance DA. 1988. Clinical and laboratory studies of malaria and melioidosis. Trans R Soc Trop Med Hyg, 82 (1), pp. 15-20. | Read more

Dance DA, Pearson AD, Seal DV, Lowes JA. 1987. A hospital outbreak caused by a chlorhexidine and antibiotic-resistant Proteus mirabilis. J Hosp Infect, 10 (1), pp. 10-16. | Show Abstract | Read more

An outbreak of urinary-tract infection involving a strain of Proteus mirabilis resistant to gentamicin and several other antibiotics affected 90 patients in Southampton between July 1980 and May 1985. The outbreak strain was also resistant to chlorhexidine and this, in combination with the antibiogram and Dienes' test, permitted differentiation from other P. mirabilis strains. The outbreak had features in common with other Enterobacteriaceae outbreaks, although certain aspects of the population involved have made it particularly difficult to control. The outbreak commenced shortly after the introduction of a catheter care policy which involved the use of chlorhexidine, and although the majority of the cases were colonized before this policy was enforced, chlorhexidine had been used extensively for other procedures within the district. Preliminary evidence suggests that there is no genetic linkage between the chlorhexidine and multiple antibiotic resistance.

1983. Complement Deficiency and Sporadic Meningococcal Disease New England Journal of Medicine, 309 (10), pp. 615-616. | Read more

Mead GM, Dance DA, Smith AG. 1983. Lymphadenopathy complicating hairy cell leukaemia. A case of disseminated Mycobacterium kansasii infection. Acta Haematol, 70 (5), pp. 335-336. | Show Abstract | Read more

A patient with hairy cell leukaemia is described who developed progressive lymphadenopathy, which proved to be due to Mycobacterium kansasii infection. Clinicians should be alert to this rare but well-described complication of hairy cell leukaemia. Early lymph node biopsy is recommended in patients developing otherwise unexplained fever and lymph node enlargement.

Rachlin A, Dittrich S, Phommasone K, Douangnouvong A, Phetsouvanh R, Newton PN, Dance DAB. 2016. Investigation of Recurrent Melioidosis in Lao People's Democratic Republic by Multilocus Sequence Typing. Am J Trop Med Hyg, 94 (6), pp. 1208-1211. | Show Abstract | Read more

Melioidosis is an infectious disease caused by the saprophytic bacterium Burkholderia pseudomallei In northeast Thailand and northern Australia, where the disease is highly endemic, a range of molecular tools have been used to study its epidemiology and pathogenesis. In the Lao People's Democratic Republic (Laos) where melioidosis has been recognized as endemic since 1999, no such studies have been undertaken. We used a multilocus sequence typing scheme specific for B. pseudomallei to investigate nine cases of culture-positive recurrence occurring in 514 patients with melioidosis between 2010 and 2015: four were suspected to be relapses while the other five represented reinfections. In addition, two novel sequence types of the bacterium were identified. The low overall recurrence rates (2.4%) and proportions of relapse and reinfection in the Laos are consistent with those described in the recent literature, reflecting the effective use of appropriate antimicrobial therapy.

Beardsley J, Wolbers M, Kibengo FM, Ggayi A-BM, Kamali A, Cuc NTK, Binh TQ, Chau NVV, Farrar J, Merson L et al. 2016. Adjunctive Dexamethasone in HIV-Associated Cryptococcal Meningitis. N Engl J Med, 374 (6), pp. 542-554. | Show Abstract | Read more

BACKGROUND: Cryptococcal meningitis associated with human immunodeficiency virus (HIV) infection causes more than 600,000 deaths each year worldwide. Treatment has changed little in 20 years, and there are no imminent new anticryptococcal agents. The use of adjuvant glucocorticoids reduces mortality among patients with other forms of meningitis in some populations, but their use is untested in patients with cryptococcal meningitis. METHODS: In this double-blind, randomized, placebo-controlled trial, we recruited adult patients with HIV-associated cryptococcal meningitis in Vietnam, Thailand, Indonesia, Laos, Uganda, and Malawi. All the patients received either dexamethasone or placebo for 6 weeks, along with combination antifungal therapy with amphotericin B and fluconazole. RESULTS: The trial was stopped for safety reasons after the enrollment of 451 patients. Mortality was 47% in the dexamethasone group and 41% in the placebo group by 10 weeks (hazard ratio in the dexamethasone group, 1.11; 95% confidence interval [CI], 0.84 to 1.47; P=0.45) and 57% and 49%, respectively, by 6 months (hazard ratio, 1.18; 95% CI, 0.91 to 1.53; P=0.20). The percentage of patients with disability at 10 weeks was higher in the dexamethasone group than in the placebo group, with 13% versus 25% having a prespecified good outcome (odds ratio, 0.42; 95% CI, 0.25 to 0.69; P<0.001). Clinical adverse events were more common in the dexamethasone group than in the placebo group (667 vs. 494 events, P=0.01), with more patients in the dexamethasone group having grade 3 or 4 infection (48 vs. 25 patients, P=0.003), renal events (22 vs. 7, P=0.004), and cardiac events (8 vs. 0, P=0.004). Fungal clearance in cerebrospinal fluid was slower in the dexamethasone group. Results were consistent across Asian and African sites. CONCLUSIONS: Dexamethasone did not reduce mortality among patients with HIV-associated cryptococcal meningitis and was associated with more adverse events and disability than was placebo. (Funded by the United Kingdom Department for International Development and others through the Joint Global Health Trials program; Current Controlled Trials number, ISRCTN59144167.).

Limmathurotsakul D, Golding N, Dance DA, Messina JP, Pigott DM, Moyes CL, Rolim DB, Bertherat E, Day NP, Peacock SJ, Hay SI. 2016. Predicted global distribution of Burkholderia pseudomallei and burden of melioidosis. Nat Microbiol, 1 (1), | Show Abstract | Read more

Burkholderia pseudomallei, a highly pathogenic bacterium that causes melioidosis, is commonly found in soil in Southeast Asia and Northern Australia1,2. Melioidosis can be difficult to diagnose due to its diverse clinical manifestations and the inadequacy of conventional bacterial identification methods3. The bacterium is intrinsically resistant to a wide range of antimicrobials, and treatment with ineffective antimicrobials may result in case fatality rates (CFRs) exceeding 70%4,5. The importation of infected animals has, in the past, spread melioidosis to non-endemic areas6,7. The global distribution of B. pseudomallei and burden of melioidosis, however, remain poorly understood. Here, we map documented human and animal cases, and the presence of environmental B. pseudomallei, and combine this in a formal modelling framework8-10 to estimate the global burden of melioidosis. We estimate there to be 165,000 (95% credible interval 68,000-412,000) human melioidosis cases per year worldwide, of which 89,000 (36,000-227,000) die. Our estimates suggest that melioidosis is severely underreported in the 45 countries in which it is known to be endemic and that melioidosis is likely endemic in a further 34 countries which have never reported the disease. The large numbers of estimated cases and fatalities emphasise that the disease warrants renewed attention from public health officials and policy makers.

Dance DAB. 2015. Editorial commentary: melioidosis in Puerto Rico: the iceberg slowly emerges. Clin Infect Dis, 60 (2), pp. 251-253. | Read more

Dance DAB, Davong V, Soeng S, Phetsouvanh R, Newton PN, Turner P. 2014. Trimethoprim/sulfamethoxazole resistance in Burkholderia pseudomallei. Int J Antimicrob Agents, 44 (4), pp. 368-369. | Read more

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Dance D. 2014. Treatment and prophylaxis of melioidosis International Journal of Antimicrobial Agents, 43 (4), pp. 310-318. | Show Abstract | Read more

Melioidosis, infection with Burkholderia pseudomallei, is being recognised with increasing frequency and is probably more common than currently appreciated. Treatment recommendations are based on a series of clinical trials conducted in Thailand over the past 25 years. Treatment is usually divided into two phases: in the first, or acute phase, parenteral drugs are given for =10 days with the aim of preventing death from overwhelming sepsis; in the second, or eradication phase, oral drugs are given, usually to complete a total of 20 weeks, with the aim of preventing relapse. Specific treatment for individual patients needs to be tailored according to clinical manifestations and response, and there remain many unanswered questions. Some patients with very mild infections can probably be cured by oral agents alone. Ceftazidime is the mainstay of acute-phase treatment, with carbapenems reserved for severe infections or treatment failures and amoxicillin/clavulanic acid (co-amoxiclav) as second-line therapy. Trimethoprim/sulfamethoxazole (co-trimoxazole) is preferred for the eradication phase, with the alternative of co-amoxiclav. In addition, the best available supportive care is needed, along with drainage of abscesses whenever possible. Treatment for melioidosis is unaffordable for many in endemic areas of the developing world, but the relative costs have reduced over the past decade. Unfortunately there is no likelihood of any new or cheaper options becoming available in the immediate future. Recommendations for prophylaxis following exposure to B. pseudomallei have been made, but the evidence suggests that they would probably only delay rather than prevent the development of infection. © 2014 The Author.

Limmathurotsakul D, Dance DAB, Wuthiekanun V, Kaestli M, Mayo M, Warner J, Wagner DM, Tuanyok A, Wertheim H, Yoke Cheng T et al. 2013. Systematic review and consensus guidelines for environmental sampling of Burkholderia pseudomallei. PLoS Negl Trop Dis, 7 (3), pp. e2105. | Show Abstract | Read more

BACKGROUND: Burkholderia pseudomallei, a Tier 1 Select Agent and the cause of melioidosis, is a Gram-negative bacillus present in the environment in many tropical countries. Defining the global pattern of B. pseudomallei distribution underpins efforts to prevent infection, and is dependent upon robust environmental sampling methodology. Our objective was to review the literature on the detection of environmental B. pseudomallei, update the risk map for melioidosis, and propose international consensus guidelines for soil sampling. METHODS/PRINCIPAL FINDINGS: An international working party (Detection of Environmental Burkholderia pseudomallei Working Party (DEBWorP)) was formed during the VIth World Melioidosis Congress in 2010. PubMed (January 1912 to December 2011) was searched using the following MeSH terms: pseudomallei or melioidosis. Bibliographies were hand-searched for secondary references. The reported geographical distribution of B. pseudomallei in the environment was mapped and categorized as definite, probable, or possible. The methodology used for detecting environmental B. pseudomallei was extracted and collated. We found that global coverage was patchy, with a lack of studies in many areas where melioidosis is suspected to occur. The sampling strategies and bacterial identification methods used were highly variable, and not all were robust. We developed consensus guidelines with the goals of reducing the probability of false-negative results, and the provision of affordable and 'low-tech' methodology that is applicable in both developed and developing countries. CONCLUSIONS/SIGNIFICANCE: The proposed consensus guidelines provide the basis for the development of an accurate and comprehensive global map of environmental B. pseudomallei.

Currie BJ, Dance DAB, Cheng AC. 2008. The global distribution of Burkholderia pseudomallei and melioidosis: an update. Trans R Soc Trop Med Hyg, 102 Suppl 1 (SUPPL. 1), pp. S1-S4. | Show Abstract | Read more

While Southeast Asia and northern Australia are well recognized as the major endemic regions for melioidosis, recent reports have expanded the endemic zone. Severe weather events and environmental disasters such as the 2004 Asian tsunami have unmasked locations of sporadic cases and have reconfirmed endemicity in Indonesia. The endemic region now includes the majority of the Indian subcontinent, southern China, Hong Kong and Taiwan. Sporadic cases have occurred in Brazil and elsewhere in the Americas and in island communities such as New Caledonia, in the Pacific Ocean, and Mauritius in the Indian Ocean. Some of the factors that are critical to further elucidating the global distribution of Burkholderia pseudomallei and melioidosis include improved access to diagnostic laboratory facilities and formal confirmation of the identity of bacterial isolates from suspected cases.

Dance DA. 2000. Melioidosis as an emerging global problem. Acta Trop, 74 (2-3), pp. 115-119. | Show Abstract | Read more

There is remarkably little known about the incidence of melioidosis outside a few countries (Thailand, Australia, Singapore and Malaysia). Presumably it is widespread in tropical south east Asia. Elsewhere there are tantalising glimpses of the tip of what may be a large iceberg. Since a specific diagnosis of melioidosis requires awareness on the part of clinicians, and the existence of a laboratory capable of isolating and identifying Burkholderia pseudomallei, a luxury not available in most rural tropical areas, the size of this iceberg is likely to remain unknown for the foreseeable future. There is mounting evidence that the disease is endemic in the Indian sub-continent and the Caribbean, and there have been unsubstantiated reports of recent cases in South Africa and the Middle East. It is unclear whether melioidosis has really spread to such areas relatively recently, or has been there but unrecognised for a long time. Almost all cases diagnosed in temperate climates have been imported from the tropics, with the exception of a unique outbreak which occurred in France in the mid-1970s. With increasing world wide travel of both humans and other animals, the potential exists for melioidosis to spread to new and fertile pastures.

Wuthiekanun V, Smith MD, Dance DA, Walsh AL, Pitt TL, White NJ. 1996. Biochemical characteristics of clinical and environmental isolates of Burkholderia pseudomallei. J Med Microbiol, 45 (6), pp. 408-412. | Show Abstract | Read more

The biochemical characteristics of 213 isolates of Burkholderia pseudomallei from patients with melioidosis and 140 isolates from the soil in central and northeastern Thailand were compared. Whereas the biochemical profiles of all the clinical isolates were similar, all soil isolates from the central area and 25% of isolates from northeastern Thailand comprised a different phenotype. This was characterised by the ability to assimilate L-arabinose (100%), adonitol (100%), 5-keto-gluconate (90%) and D-xylose (84%), but failure to assimilate dulcitol (0%), erythritol (0%) and trehalose (10%). Compared with clinical isolates, these organisms had similar antibiotic susceptibility profiles and were also recognised by a specific polyclonal antibody against B. pseudomallei. As melioidosis is rare in central Thailand, but common in the northeast, this raises the possibility that this biochemical phenotype may be less virulent, or may even represent a different species.

Suputtamongkol Y, Rajchanuwong A, Chaowagul W, Dance DA, Smith MD, Wuthiekanun V, Walsh AL, Pukrittayakamee S, White NJ. 1994. Ceftazidime vs. amoxicillin/clavulanate in the treatment of severe melioidosis. Clin Infect Dis, 19 (5), pp. 846-853. | Show Abstract | Read more

An open, paired, randomized, controlled trial of high-dose parenteral ceftazidime (120 mg/[kg.d]) vs. amoxicillin/clavulanate (160 mg/[kg.d]) for the treatment of severe melioidosis was conducted in Ubon Ratchatani in northeastern Thailand. Of 379 patients enrolled in the study, 212 (56%) had culture-proven melioidosis; 106 patients were in each treatment group. The overall mortality rate (47%) was similar for both treatment groups. However, 4 of 75 surviving patients in the ceftazidime group compared with 16 of 69 surviving patients in the amoxicillin/clavulanate group were switched to the alternate regimen because of an unsatisfactory clinical response after > or = 72 hours of treatment (P = .004). The overall therapeutic failure rate (i.e., treatment failure or death due to uncontrolled melioidosis) was significantly higher for the amoxicillin/clavulanate group than for the ceftazidime group (P = .02). Clinical and bacteriologic responses for successfully treated patients were similar in both groups, and both treatments were well tolerated. Parenteral amoxicillin/clavulanate is a safe and effective initial treatment, but parenteral ceftazidime remains the treatment of choice for severe melioidosis.

Suputtamongkol Y, Hall AJ, Dance DA, Chaowagul W, Rajchanuvong A, Smith MD, White NJ. 1994. The epidemiology of melioidosis in Ubon Ratchatani, northeast Thailand. Int J Epidemiol, 23 (5), pp. 1082-1090. | Show Abstract | Read more

BACKGROUND: Melioidosis, or infection with Pseudomonas pseudomallei is an important cause of morbidity and mortality in South East Asia and Northern Australia. The epidemiology of melioidosis in Ubon Ratchatani, Northeast Thailand was studied over a 5-year period from 1987 to 1991. METHODS: Rates and, when possible, the risks of developing melioidosis were calculated. The numerator was the number of culture-proven cases of melioidosis seen in the 1000-bed referral hospital of the province. The denominators were obtained from the population census, a survey of Health, Welfare and Use of Traditional Medicine, and the North Eastern Meterological Centre, Thailand. RESULTS: The average incidence of human melioidosis was 4.4 (95% confidence interval [CI]: 3.8-5.0) per 100,000. The disease affected all ages with the highest incidence in 40-60 years olds. Melioidosis was 1.4 (95% CI: 0.4-5.3) times more common in males than females. The disease showed a significant seasonal variation in incidence, and a strong linear correlation with rainfall (r = 0.7, 95% CI: 0.5-0.9) Adults exposed to soil and water in their work (most were rice farmers) had an increased risk of melioidosis (in the 40-59 year age group, relative risk = 4.1, 95% CI: 2.4-6.9). Most adult patients had an underlying disease (mainly diabetes mellitus) predisposing them to this infection. CONCLUSION: Melioidosis may result from either acute exposure to the organism in the soil and water, or 're-activation' of an asymptomatic childhood infection (by an unidentified possibly infective seasonal cofactor). The results from this analysis are consistent with both hypotheses. Further epidemiological studies are needed to identify risk factors so that optimal strategies for control of melioidosis may be developed.

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