鸡来源产超广谱β-内酰胺酶大肠埃希菌携带整合子基因的研究

Study on integrons in Escherichia coli which producing extended-spectrum β-lactamases, isolated from stool specimen of chicken

目的分析鸡肠道内共生的产超广谱β-内酰胺酶（ESBLs）大肠埃希菌整合子携带状况以及其与多重耐药性的关系。方法从甘肃、湖北、北京、四川地区养殖场鸡粪便标本中分离的大肠埃希菌，肉汤稀释法检测菌株的耐药性，WHONET软件进行耐药性分析；筛选出的ESBLs菌株进行整合子的PCR检测和基因测序。结果通过药敏试验从鸡粪中分离的224株大肠埃希菌中共检出产ESBLs的菌株54株，分离率为24．1％。产ESBLs的菌株中Ⅰ类整合子的携带率为63．0％，Ⅰ类整合子可变区发现的耐药基因有aadA1、aadA2、aadA5、aadA22，dfrA12、dfrA17、dfrI，aar-3，分别介导氨基糖苷类、磺胺类抗生素以及利福平的耐药性。aadA22是在国内菌株中首次报道。Ⅱ类整合子携带率为5．6％，携带的耐药基因包括sat、ereA、aadA1。Ⅲ类整合子酶阳性的有3株菌，但其可变区未检出任何耐药基因。结论Ⅰ类整合子主要介导氨基糖苷类抗生素和甲氧嘧啶的耐药性，在大肠埃希菌ESBLs菌株的多重耐药性中具有重要的作用，加强养殖动物大肠埃希菌耐药性以及整合子携带状况的监测，对防止耐药菌株的广泛传播，改善临床抗生素的疗效具有重要意义。

Objective To analysis the dissemination of integrons in the extended-spectrum β-lactamases（ESBLs） producing Escherichia coli, isolated from stool specimen of chicken and to study the relations between the resistance and the integrons of these isolates. Methods The Escherichia coli isolates were collected from Gansu, Hubei, Sichuan provinces and Beijing municipal city, and were isolated from stool specimen of chickens. Using WHONET software, the Escherichia coli producing ESBLs were selected, and then detected by PCR method class 1,2,3,4 integrase. PCR products of the variable region of the integron were sequenced. Results 54 of the 224 （24.1% ） isolates were ESBLs producing Escherichia coli. Class 1 integron were detected in 63.0 % of the isolates, and aadA 1, aadA 2 , aadA 5, aadA 22 , dfrA12, dfrA 17, dfrI, aar-3 were found in the variable region and aadA gene encodes resistant to streptomycin, spectinomycin, dfr gene to trimethoprim and aar to rifampicin. We realized that aadA22 was the first time detected in China. Class 2 integron were detected in 5.6 % of the isolates, Class 3 integron was detected in 3 isolates. Conclusion Class 1 integron was the most commonly seen integron in Escherichia coli, encoding the resistance to streptomycin,spectinomycin and trimethoprim. Integrons were contributed to the horizontal transfer of resistant genes in the same or different species, suggesting that the antimicrobial resistance and the dissemination of integrons should be monitored.