Emergence of in Diseased Pigs in South Korea.

We examined the prevalence and molecular characteristics of carrying colistin-resistant among cattle, pig, and chicken isolates in South Korea. Among a total of 185 colistin-resistant isolates determined in this study (47 from cattle, 90 from pigs, and 48 from chicken), PCR amplification detected - genes in 17 isolates predominantly from diseased pigs. The - genes were characterized as in 15 isolates and - in 2 isolates. The gene was transferred to the J53 recipient strain from more than 50% of the --carrying isolates. The -1 and - genes were identified predominantly in IncHI2 and IncP plasmids, respectively. Multi-locus sequence typing analysis revealed eight previously reported sequence types (ST), including ST1, ST10, and ST42. We identified isolates with similar pulsed-field gel electrophoresis patterns from diseased pigs in three farms. Besides, the isolates carried various virulence factors and demonstrated resistance to multiple antimicrobials, including β-lactams and quinolones. Further, the - encodes three amino acid substitutions compared with -1. To the best of our knowledge, this is the first report of pathogenic carrying - in South Korea, which implies that - variants may have already been widely spread in the pig industry.