Supplementary of: Klebsiella pneumoniae with capsule type K64 is overrepresented among invasive disease in Vietnam

Introduction: Recent reports indicate the emergence of community-acquired pneumonia associated with K64-Klebsiella pneumoniae. Here, we identify the capsular types and sequence type of invasive and commensal K. pneumoniae isolates from Vietnam.

Methods: We included 93 K. pneumoniae isolates from patients hospitalized at the National Hospital for Tropical Diseases, Hanoi between 2007 and 2011; and 110 commensal isolates from throat swabs from healthy volunteers living in rural and urban Hanoi in 2012. We determined sequence types by multi-locus sequence typing (MLST) and capsule typing for seven K types by PCR. Antibiotic susceptibility testing was performed using disk diffusion.

Results: The most common detected capsule types were K1 (39/203, 19.2%, mainly ST23) and K2 (31/203, 15.3%, multiple STs: ST65, ST86, ST380). We found significantly more K2 isolates among invasive in comparison to commensal isolates (22.6% vs 9%, p = 0.01) but no significant difference was observed between invasive and commensal K1 isolates (14.5% vs 24.7%, p = 0.075). K64 with varying sequence types were predominantly seen among invasive K. pneumoniae (8 vs. 3) and were isolated from sepsis and meningitis patients. Among K64 isolates, one was carbapenem-resistant with ST799.

Conclusion: Our study confirms that capsule type K64 K. pneumoniae is associated with community-acquired invasive infections in Vietnam. Research is needed to unravel the mechanisms of virulence of capsule typeK64 in both community and hospital setting.

Methods
The data contains the results of experiments which were designed to identify the K serotypes of Klebsiella pneumoniae and the procedure was followed the protocols in the publication in the links: https://pubmed.ncbi.nlm.nih.gov/19785524 and https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0080670