Colonization with Staphylococcus aureus and Klebsiella pneumoniae causes infections in a Vietnamese intensive care unit
Thuy DB., Campbell J., Thuy CT., Hoang NVM., Voong Vinh P., Nguyen TNT., Nguyen Ngoc Minh C., Pham DT., Rabaa MA., Lan NPH., Hao NV., Thwaites GE., Thwaites CL., Baker S., Chau NVV., Chung The H.
<jats:p>Pre-existing colonization with <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.11043" xlink:type="simple">Staphylococcus aureus</jats:ext-link> </jats:named-content> </jats:italic> or <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.10789" xlink:type="simple">Klebsiella pneumoniae</jats:ext-link> </jats:named-content> </jats:italic> has been found to increase the risk of infection in intensive care patients. We previously conducted a longitudinal study to characterize colonization of these two organisms in patients admitted to intensive care in a hospital in southern Vietnam. Here, using genomic and phylogenetic analyses, we aimed to assess the contribution these colonizing organisms made to infections. We found that in the majority of patients infected with <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.11043" xlink:type="simple">S. aureus</jats:ext-link> </jats:named-content> </jats:italic> or <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.10789" xlink:type="simple">K. pneumoniae</jats:ext-link> </jats:named-content> </jats:italic>, the sequence type of the disease-causing (infecting) isolate was identical to that of corresponding colonizing organisms in the respective patient. Further in-depth analysis revealed that in patients infected by <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.11043" xlink:type="simple">S. aureus</jats:ext-link> </jats:named-content> </jats:italic> ST188 and by <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.10789" xlink:type="simple">K. pneumoniae</jats:ext-link> </jats:named-content> </jats:italic> ST17, ST23, ST25 and ST86, the infecting isolate was closely related to and exhibited limited genetic variation relative to pre-infection colonizing isolates. Multidrug-resistant <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.11043" xlink:type="simple">S. aureus</jats:ext-link> </jats:named-content> </jats:italic> ST188 was identified as the predominant agent of colonization and infection. Colonization and infection by <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.10789" xlink:type="simple">K. pneumoniae</jats:ext-link> </jats:named-content> </jats:italic> were characterized by organisms with limited antimicrobial resistance profiles but extensive repertoires of virulence genes. Our findings augment the understanding of the link between bacterial colonization and infection in a low-resource setting, and could facilitate the development of novel evidence-based approaches to prevent and treat infections in high-risk patients in intensive care.</jats:p>