No abstract

The emergence of Enterobacteriaceae strains resistant to both colistin and carbapenem, which harbor the mobile colistin resistance (mcr) gene, has become a significant clinical and public health concern. The aim of this study was to identify strains with co-resistance to carbapenem and colistin and gain further understanding of the antimicrobial characteristics of these strains in South Korea. Bacterial identification was performed using MALDI Biotyper and Vitek2 compact, antibiotic susceptibility was tested using broth microdilution and agar disk diffusion, and the antimicrobial resistance genes were detected using polymerase chain reaction. Pulsed-field gel electrophoresis (PFGE) was used to compare and identify strains with co-resistance to carbapenem and colistin. In this study, a total of 66 (9.9%) clinical isolates of Enterobacteriaceae were obtained, all of which exhibited concurrent resistance to both carbapenem and colistin. Among these isolates, seven carried the mcr-8 (n=1), mcr-9 (n=5), and mcr-10 (n=1) genes, respectively. Notably, five clinical isolates with an identical pulsotype of Enterobacter cloacae complex were obtained from patients at the same hospital, while 11 isolates of Klebsiella pneumoniae were obtained from patients at the same or different hospitals in Gangwon Province, South Korea. Fortunately, none of the Klebsiella pneumoniae isolates that were transmitted carried the mcr gene. To the best of our knowledge, this is the confirmation of the transmission and circulation of carbapenem-and colistin-resistant Enterobacteriaceae strains in a nosocomial and/or local community setting in South Korea. These results underscore the importance of implementing effective infection control measures and continuously monitoring resistant bacteria.