# Characterization of Antimicrobial Resistance and Hypervirulent Traits of Klebsiella variicola Isolates Collected in South Korea

## TL;DR

This study examines antimicrobial resistance and virulence traits in Klebsiella variicola isolates from South Korea, finding low resistance rates but some multidrug-resistant strains.

## Contribution

The study provides the first characterization of antimicrobial resistance and hypervirulent traits in K. variicola isolates from South Korea.

## Key findings

- Most isolates were susceptible to all tested antimicrobials.
- One isolate carried the blaKPC-2 gene on an IncX3 plasmid.
- Ten isolates showed a mucoid phenotype, mainly with KL60 and KL61 capsular types.

## Abstract

Introduction: Klebsiella variicola, a member of Klebsiella pneumoniae complex, has emerged as an opportunistic pathogen for human infection; however, antimicrobial resistance and hypervirulent characteristics of K. variicola have rarely been investigated in South Korea. Methods: We analyzed 76 clinical K. variicola isolates collected from 12 hospitals between September 2022 and October 2023. Bacterial identification was performed by MALDI-TOF MS. Antimicrobial susceptibility was tested by disk diffusion tests. Resistance determinants and virulence traits were investigated, and whole-genome sequencing was performed for hypermucoviscous or carbapenem-resistant K. variicola isolates. Results: Most (89.5%, 68/76) were susceptible to all 18 antimicrobials tested in this study, and 3 isolates harbored blaCTX-M-15. One isolate carried blaKPC-2 on its IncX3 plasmid, which is closely related to carbapenem-resistant K. pneumoniae plasmids. Capsular typing revealed 51 wzi allelic types. Ten isolates showed mucoid phenotype, mainly with KL60 and KL61. Conclusions: This study reveals relatively low resistance rates in K. variicola strains but the presence of multidrug-resistant and hypermucoviscous K. variicola strains. In addition, the evidence of interspecies dissemination of blaKPC-2 highlights the need for continuous genomic surveillance.