Colonization and infection in a Vietnamese ICU

Colonization with Staphylococcus aureus or Klebsiella pneumoniae has been found to increase the risk of infection in intensive care patients. We previously conducted a cohort study to characterize the colonization of these two pathogens in intensive care patients in Southern Vietnam, and herein used genomic and phylogenetic analyses to examine their contribution to infections. We found that in the majority of patients infected with S. aureus or K. pneumonaie, the infecting genotype was identical to that of colonizing strains in the respective patient. In-depth analysis revealed that in cases infected by S. aureus ST188 and K. pneumoniae ST17, ST23 and ST86, the infecting isolate was closely related to and shared little genetic variation with the pre-infection colonizing isolates. Methicillin-resistant ST188 S. aureus emerged as a predominant agent of colonization and infection, which is both highly virulent and multidrug resistant. In contrast, the colonization and infection by K. pneumoniae were characterized by low antimicrobial resistance profile but high virulent potential. Our findings enhance the understanding of bacterial colonization and infections in a low-resource setting, and could enable novel and evidence-based diagnostics and therapeutics to prevent and treat infections in intensive care patients.