Prevalence and Genetic Characterization of mcr-1 -Positive Escherichia coli Isolated from Retail Meats in South Korea

The spread of plasmid-mediated colistin resistance has posed a serious threat to public health owing to its effects on the emergence of pandrug-resistant bacteria. In this study, we investigated the prevalence and characteristics of -positive isolated from retail meat samples in Korea. In total, 1,205 strains were isolated from 3,234 retail meat samples in Korea. All strains were subjected to antimicrobial susceptibility testing and were examined for the presence of gene. All -positive ( = 10, 0.8%) from retail meat were subjected to pulse-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS). The transferability of gene was determined by conjugation assays. The -positive strains exhibited diverse clonal types. Our genes were located in plasmids belonged to the IncI2 ( = 1) and IncX4 ( = 8) types, which were reported to be prevalent in Asia and worldwide, respectively. Most genes from -positive strains (9/10) were transferable to the recipient strain and the transfer frequencies ranged from 2.4 × 10 to 9.8 × 10 . Our data suggest that the specific types of plasmid may play an important role in spreading plasmid-mediated colistin resistance in Korea. Furthermore, our findings suggest that the retail meat may be an important tool for disseminating plasmid-mediated colistin resistance.