Low prevalence of methicillin-resistant Staphylococcus aureus (MRSA) carriage at hospital admission in the Netherlands

Objective. To determine the prevalence of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) at admission of patients without risk factors for MRSA carriage. (MSRA constitutes less than 1% of clinical S. aureus strains in the Netherlands; there is a national 'search and destroy' policy.) Design. Surveillance study. Method. Patients admitted to non-surgical departments in the period 1999-2000 were screened for MRSA nasal carriage in 4 Dutch hospitals. Nasal swabs were streaked on blood agar, submerged in a selective broth, and incubated for 2-3 days at 35°C. Colonies suspected for S. aureus were identified with standard microbiological techniques. Susceptibility testing was performed by an automated system and oxacillin disk diffusion. Strains suspected for methicillin resistance were confirmed by a DNA hybridization test and MecA PCR. MRSA strains were genotyped by pulsed-field gel electrophoresis (PFGE). Results. Twenty-four per cent (2332/9859) of the patients were nasal carriers of S. aureus. Three (0.03%) patients were MRSA carrier. These patients were not repatriated from foreign hospitals and not known to be MRSA carriers before admission. Genotyping revealed that the strains were not clonally related and were not related to MRSA outbreaks in the same hospital. Conclusion. At routine admission to a Dutch hospital (excluding high-risk admissions such as from abroad) the MRSA prevalence was low (0.03%), probably due to the Dutch search-and-destroy policy and restrictive antibiotic prescribing.