title: Dissemination of the chromosomally encoded CMY-2 cephalosporinase gene in Escherichia coli isolated from animals.
abstract: In this study, 619 individual Escherichia coli isolates from food-producing and companion animals were analysed to determine the prevalence of the cephalosporinase gene blaCMY-2. In total, 18 CMY-2-producers (2.9%) were detected and exhibited multidrug-resistant phenotypes. One of the CMY-2-producers was found to possess a novel blaCMY-2-like allele, blaCMY-130. The isolates belonged to distinct pulsotypes, suggesting that the blaCMY-2 gene was not disseminated by clonal expansion of blaCMY-2-positive strains. The blaCMY-2 genes were located on IncA/C-, IncHI2- or IncX-type plasmids in 9 (50%) of the 18 E. coli isolates. However, in the other nine isolates I-CeuI-PFGE and hybridisation analyses revealed that the blaCMY-2 gene was chromosomally located. A CMY gene-containing region composed of five open reading frames (ORFs) (ISEcp1-blaCMY-2-blc-sugE-ΔencR) was observed in plasmids from eight strains. A CMY gene-containing region composed of ten ORFs was observed in all of the nine chromosomally encoded blaCMY-2 genes, including a putative IS66-like element inserted in this conserved CMY genetic region in three strains. This conserved CMY genetic region was also found to be inserted into the oriVγ (putative gamma origin), part of the IncX plasmid backbone, by a complete transposition unit flanked by 5-bp DRs (direct repeat sequence) in pS62T. These results demonstrate the high prevalence of the chromosomally encoded blaCMY-2 gene in E. coli. This is the first study reporting a chromosomally encoded blaCMY-2 gene in E. coli. Chromosomally encoded blaCMY-2 might be a source of some plasmid-mediated blaCMY-2 genes and this probably facilitates the spread of cephalosporin-resistant strains.
authors.affiliation: Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, PR China.
authors.forename: Liang-Xing
authors.initials: LX
authors.lastname: Fang
authors.affiliation: Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.affiliation: Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, PR China.
authors.forename: Liang
authors.initials: L
authors.lastname: Li
authors.affiliation: Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Deng
authors.affiliation: Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, PR China.
authors.forename: Ting
authors.initials: T
authors.lastname: Huang
authors.affiliation: Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, PR China.
authors.forename: Qiu-E
authors.initials: QE
authors.lastname: Yang
authors.affiliation: Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, PR China.
authors.forename: Xue
authors.initials: X
authors.lastname: Li
authors.affiliation: Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, PR China.
authors.forename: Mu-Ya
authors.initials: MY
authors.lastname: Chen
authors.affiliation: Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, PR China.
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Liao
authors.affiliation: Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, PR China; Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, PR China. Electronic address: gale@scau.edu.cn.
authors.forename: Ya-Hong
authors.initials: YH
authors.lastname: Liu
mesh_terms: D000818:Animals; D000829:Animals, Domestic; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002876:Chromosomes, Bacterial; D017124:Conserved Sequence; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D023061:Gene Order; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D058889:Molecular Typing; D057805:Pets; D010957:Plasmids / Q000032:analysis; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; C103022:beta-lactamase CMY-2; D001618:beta-Lactamases
keywords: AmpC; Chromosome; Enterobacteriaceae, ISEcp1; bla(CMY-2)