Identification of the multi-resistance gene cfr in Escherichia coli isolates of animal origin

PLoS One. 2014 Jul 18;9(7):e102378. doi: 10.1371/journal.pone.0102378. eCollection 2014.

Abstract

Previous study indicated that the multi-resistance gene cfr was mainly found in gram-positive bacteria, such as Staphylococcus and Enterococcus, and was sporadically detected in Escherichia coli. Little is known about the prevalence and transmission mechanism of cfr in E. coli. In this study, the presence of cfr in E. coli isolates collected during 2010-2012 from food-producing animals in Guangdong Province of China was investigated, and the cfr-positive E. coli isolates were characterized by PFGE, plasmid profiling, and genetic environment analysis. Of the 839 E. coli isolates, 10 isolates from pig were cfr positive. All the cfr-positive isolates presented a multi-resistance phenotype and were genetically divergent as determined by PFGE. In 8 out of the 10 strains, the cfr gene was located on plasmids of ∼30 kb. Restriction digestion of the plasmids with EcoRI and sequence hybridization with a cfr-specific probe revealed that the cfr-harboring fragments ranged from 6 to 23 kb and a ∼18 kb cfr-carrying fragment was common for the plasmids that were ∼30 kb. Four different genetic environments of cfr were detected, in which cfr is flanked by two identical copies of IS26, which may loop out the intervening sequence through homologous recombination. Among the 8 plasmids of ∼30 kb, 7 plasmids shared the same genetic environment. These results demonstrate plasmid-carried cfr in E. coli and suggest that transposition and homologous recombination mediated by IS26 might have played a rule in the transfer of the cfr gene in E. coli.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Drug Resistance, Multiple / genetics*
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Escherichia coli / drug effects*
  • Escherichia coli / genetics*
  • Escherichia coli / isolation & purification
  • Escherichia coli Proteins / genetics*
  • Gene Transfer, Horizontal
  • Homologous Recombination
  • Methyltransferases / genetics*
  • Molecular Sequence Data
  • Plasmids / genetics
  • Swine / microbiology*

Substances

  • Escherichia coli Proteins
  • Cfr protein, E coli
  • Methyltransferases

Associated data

  • GENBANK/KJ453114
  • GENBANK/KJ453115
  • GENBANK/KJ453116
  • GENBANK/KJ453117

Grants and funding

This work was supported by the National Science Fund for Distinguished Young Scholars (Grant No. 31125026), the National Natural Science Foundation (Grant No. 31272609), Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (Grant No. IRT13063) and Science and Technology Program of Guangzhou, China (Grant No. 2011J2200054). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.