title: Identification of the multi-resistance gene cfr in Escherichia coli isolates of animal origin.
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.
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Deng
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Li
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou, China.
authors.forename: Liang-Xing
authors.initials: LX
authors.lastname: Fang
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou, China.
authors.forename: Qijing
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou, China.
authors.forename: Ya-Hong
authors.initials: YH
authors.lastname: Liu
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues (SCAU), South China Agricultural University, Guangzhou, China.
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Liao
mesh_terms: D000818:Animals; D018432:Drug Resistance, Multiple / Q000235:genetics*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D029968:Escherichia coli Proteins / Q000235:genetics*; D022761:Gene Transfer, Horizontal; D059765:Homologous Recombination; D008780:Methyltransferases / Q000235:genetics*; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D013552:Swine / Q000382:microbiology*
chemical_list: D029968:Escherichia coli Proteins; C534716:Cfr protein, E coli; D008780:Methyltransferases