Plasmids of the incompatibility group FIBK occur in Klebsiella variicola from diverse ecological niches.

Abstract

Plasmids play a fundamental role in the evolution of bacteria by allowing them to adapt to different environments and acquire, through horizontal transfer, genes that confer resistance to different classes of antibiotics. Using the available in vitro and in silico plasmid typing systems, we analyzed a set of isolates and public genomes of K. variicola to study its plasmid diversity. The resistome, the plasmid multilocus sequence typing (pMLST), and molecular epidemiology using the MLST system were also studied.A high frequency of IncF plasmids from human isolates but lower frequency from plant isolates were found in our strain collection.Insilico detection revealed 297 incompatibility (Inc) groups, but the IncFIBK(216/297) predominated in plasmids from human and environmentalsamples, followed by IncFIIK(89/297) and IncFIA/FIA(HI1) (75/297). These Inc groups were associated with clinically important ESBL (CTX-M-15), carbapenemases (KPC-2 and NDM-1), and colistin-resistant genes which were associated withmajor sequence types (ST): ST60, ST20, andST10. Insilico MOB typing showed 76% (311/404) of the genomes contained one or more of the six relaxase families with MOBFbeing most abundant. We identified untypeable plasmids carrying blaKPC-2, blaIMP-1, and blaSHV-187 but for which a relaxase was found; this may suggest that novel plasmid structures could be emerging in this bacterial species. The plasmid content in K. variicola has limited diversity, predominantly composed of IncFIBK plasmids dispersed in different STs. Plasmid detection using the replicon and MOB typing scheme provide a broader context of the plasmids inK. variicola. This study showed that whole-sequence-basedtyping provides current insights of the prevalence of plasmid types and their association with antimicrobial resistant genes inK. variicolaobtained from humans and environmental niches.