Isolation and plasmid characterisation of Salmonella enterica serovar Albany harbouring mcr-5 from retail chicken meat in Japan

FEMS Microbiol Lett. 2020 Aug 1;367(15):fnaa127. doi: 10.1093/femsle/fnaa127.

Abstract

The emergence of plasmid-mediated colistin resistance genes (mcr), which is occurring in numerous countries, is a worldwide concern, primarily because colistin is a last-resort antibiotic. Compared to E. coli, prevalence of mcr genes in Salmonella is unclear in Japan. Here we screened for mcr-1-5 genes in our collection of Salmonella strains isolated from retail meat products collected in Japan from 2012 through 2016. We found that Salmonella Albany strain 27A-368 encodes mcr-5 and that mcr genes were undetectable among the remaining 202 isolates. The resistance plasmid p27A-368 was transferred by conjugation to S. Infantis and was stably retained as a transconjugant. Whole-genome sequencing revealed that mcr-5 resided on a 115 kb plasmid (p27A-368). The plasmid backbone of p27A-368 is more similar to that of pCOV27, an ESBL-encoding plasmid recovered from avian pathogenic E. coli, rather than pSE13-SA01718 of S. Paratyphi B that encodes mcr-5. Further, mcr-5 is located on a transposon, and its sequence is similar to that of pSE13-SA01718. A phylogenetic tree based on single nucleotide variants implies a relationship between 27A-368 and S. Albany isolated in Southeast Asian countries.

Keywords: colistin; mcr-5; non-typhoidal Salmonella; retail chicken products; whole genome sequence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chickens
  • Food Microbiology*
  • Japan
  • Meat / microbiology*
  • Plasmids / genetics*
  • Salmonella enterica / enzymology
  • Salmonella enterica / genetics*
  • Salmonella enterica / isolation & purification*
  • Transferases (Other Substituted Phosphate Groups) / genetics

Substances

  • Transferases (Other Substituted Phosphate Groups)