title: Detection and characterisation of CTX-M and CMY-2 beta-lactamases among Escherichia coli isolates from farm animals in Guangdong Province of China.
abstract: The objective of this study was to characterise the beta-lactamase genes of cephalosporin-resistant Escherichia coli isolated from farm animals in Guangdong Province of China. Of 592 E. coli isolates recovered from farm animals from 2003-2005, 50 (8.4%) showed cephalosporin resistance. Polymerase chain reaction and sequencing analysis showed that 14 isolates (2.4%) from chickens, ducks, pigs and partridges were positive for the bla(CTX-M) gene (10 for bla(CTX-M-14) and 4 for bla(CTX-M-27)). CMY-2 was detected for the first time in mainland China in six E. coli isolates (1.0%) from chickens and goose. Except for one isolate, bla(CTX-M)- and bla(CMY-2)-containing isolates also harboured the bla(TEM-1b) gene. Conjugation experiments demonstrated that the bla(CTX-M) and bla(TEM) genes could be transferred to E. coli DH5alpha. Pulsed-field gel electrophoresis (PFGE) showed that the 14 CTX-M-producing isolates belonged to 12 different types. Two isolates (one from a chicken, the other from a pig) containing CTX-M-14 showed indistinguishable PFGE patterns, indicating clonal dissemination of this strain among animals from different farms. This study describes for the first time the emergence of CTX-M- and CMY-2-producing E. coli among farm animals in China, with the CTX-M-9 group being the predominant extended-spectrum beta-lactamase detected.
authors.affiliation: College of Veterinary Medicine, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Liu
authors.forename: Shu-Yong
authors.initials: SY
authors.lastname: Wei
authors.forename: Jun-Ying
authors.initials: JY
authors.lastname: Ma
authors.forename: Zhen-Ling
authors.initials: ZL
authors.lastname: Zeng
authors.forename: Dian-Hong
authors.initials: DH
authors.lastname: Lü
authors.forename: Gui-Xiang
authors.initials: GX
authors.lastname: Yang
authors.forename: Zhang-Liu
authors.initials: ZL
authors.lastname: Chen
mesh_terms: D000818:Animals; D000829:Animals, Domestic / Q000382:microbiology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018550:Cephalosporin Resistance; D002645:Chickens; D002681:China; D003001:Cloning, Molecular; D024881:Drug Resistance, Bacterial; D004372:Ducks; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology*; D005243:Feces / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D013552:Swine; D001618:beta-Lactamases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D001618:beta-Lactamases