Genomic analysis of pESI-like megaplasmid in Salmonella Infantis from the poultry industry in Korea

초록

The plasmid of emerging Salmonella Infantis (pESI) and pESI-like plasmids have been reported as a major cause of the dissemination of S. Infantis worldwide, and these plasmids have also been reported in Korea. In this study, eight pESI or pESI-like plasmids, including two pESI-like plasmids of S. Infantis from the poultry industry in Korea, harbored yersiniabactin operon, toxin/antitoxin systems, and fimbria clusters. Interestingly, various resistance genes were identified in the pESI-like plasmids but not in the pESI plasmid. In particular, dfrA14, which confers resistance to trimethoprim, was harbored in one copy in seven pESI or pESI-like plasmids, but the pM6-2-F5 plasmid harbored two copies. Additionally, the copy number of insertion sequence 26 in seven pESIlike plasmids was higher than in the pESI plasmid. In this study, 40 S. Infantis strains carrying the pESI or pESIlike plasmids from various countries, including two strains in Korea, were classified into two clusters, with the plasmids identified as IncI1 ST71 in cluster I and IncI1 ST209 in cluster II. The 16 strains representing IncI1 ST71 harbored blaCTX-M-65, whereas the 8 strains representing IncI1 ST209 harbored blaCTX-M-1. Our study provides valuable information on the pESI-like plasmid in S. Infantis from the poultry industry worldwide.

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