Liu Jian-Hua, Wei Shu-Yong, Ma Jun-Ying, Zeng Zhen-Ling, Lü Dian-Hong, Yang Gui-Xiang, Chen Zhang-Liu
College of Veterinary Medicine, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China.
Int J Antimicrob Agents. 2007 May;29(5):576-81. doi: 10.1016/j.ijantimicag.2006.12.015. Epub 2007 Feb 20.
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.
本研究的目的是对从中国广东省农场动物中分离出的耐头孢菌素大肠杆菌的β-内酰胺酶基因进行特征分析。在2003年至2005年从农场动物中分离出的592株大肠杆菌中，50株（8.4%）表现出对头孢菌素的耐药性。聚合酶链反应和测序分析表明，从鸡、鸭、猪和鹧鸪中分离出的14株（2.4%）bla(CTX-M)基因呈阳性（10株为bla(CTX-M-14)，4株为bla(CTX-M-27)）。CMY-2首次在中国大陆从鸡和鹅的6株大肠杆菌分离株（1.0%）中检测到。除1株分离株外，含有bla(CTX-M)和bla(CMY-2)的分离株也携带bla(TEM-1b)基因。接合实验表明，bla(CTX-M)和bla(TEM)基因可转移至大肠杆菌DH5α。脉冲场凝胶电泳（PFGE）显示，14株产CTX-M的分离株属于12种不同类型。两株含有CTX-M-14的分离株（一株来自鸡，另一株来自猪）显示出难以区分的PFGE图谱，表明该菌株在不同农场的动物之间发生了克隆传播。本研究首次描述了中国农场动物中产CTX-M和CMY-2的大肠杆菌的出现情况，其中CTX-M-9组是检测到的主要超广谱β-内酰胺酶。
