Wu Hao, Xia Shibo, Bu Fanyun, Qi Jing, Liu Yuqing, Xu Hai
State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan 250100, Shandong, China.
Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Jinan 250100, Shandong, China.
Int J Food Microbiol. 2015 Oct 15;211:51-6. doi: 10.1016/j.ijfoodmicro.2015.07.004. Epub 2015 Jul 9.
The dissemination of drug-resistant Escherichia coli in poultry products is becoming a public concern, as it endangers food security and human health. It is very common for E. coli to exhibit drug resistance in the poultry industry in China due to the excessive use of antibiotics. However, few studies have examined the drug resistance endowed by integrons and integron-associated gene cassettes in different phylogenetic groups of E. coli isolated from broiler carcasses. In this study, 373 antibiotic-resistant E. coli strains were isolated from the surfaces or insides of broiler carcasses from a slaughterhouse in Shandong Province, China. According to phylogenetic assays of chuA, yjaA, and an anonymous DNA fragment, TSPE4-C2, these isolates belong to four phylogenetic groups (A, B1, B2, and D) and seven subgroups (A0, A1, B1, B21, B22, D1, and D2). Of the tested isolates, 95.71% (n=357) are multi-drug resistant, among which group B1 was predominant, accounting for 33.51% (n=125) of the tested isolates. A high percentage of the E. coli isolates were resistant to amoxicillin-clavulanic acid (99.20%, n=370), doxycycline (92.23%, n=344), sulfamethoxazole-trimethoprim (90.88%, n=339), ciprofloxacin, (64.61%, n=241), sulbactam-cefoperazone (51.21%, n=191), and amikacin (33.78%, n=126). Furthermore, among the 373 isolates, class 1 and 2 integrons were identified in 292 (78.28%) and 49 (13.14%) of the isolates, respectively, while no class 3 integrons were detected. The most prevalent gene cassette arrays were dfrA17-aadA5 and dfrA12-orfF-aadA2 in the variable region of class 1 integrons, while only one gene cassette array (dfrA1-sat2-aadA1) was detected in the variable region of class 2 integrons. Class 1 integrons were distributed in various physiological subtypes, whereas no predominant phylogenetic groups could be identified. The presence of class 2 integrons in the B21 subtype was significantly higher than in the other subtypes, and it coexisted with the class 1 integron. This study suggests that broiler products are potential sources of multi-drug resistant E. coli, and that resistance genes could be spread by lateral gene transfer.
耐药性大肠杆菌在家禽产品中的传播正成为一个公众关注的问题，因为它危及食品安全和人类健康。由于抗生素的过度使用，大肠杆菌在中国家禽业中表现出耐药性是非常普遍的。然而，很少有研究考察从肉鸡胴体分离的不同系统发育群的大肠杆菌中整合子及整合子相关基因盒赋予的耐药性。在本研究中，从中国山东省一家屠宰场的肉鸡胴体表面或内部分离出373株耐抗生素大肠杆菌菌株。根据chuA、yjaA和一个匿名DNA片段TSPE4-C2的系统发育分析，这些分离株属于四个系统发育群（A、B1、B2和D）和七个亚群（A0、A1、B1、B21、B22、D1和D2）。在测试的分离株中，95.71%（n = 357）为多重耐药，其中B1群占主导，占测试分离株的33.51%（n = 125）。高比例的大肠杆菌分离株对阿莫西林-克拉维酸（99.20%，n = 370）、强力霉素（92.23%，n = 344）、磺胺甲恶唑-甲氧苄啶（90.88%，n = 339）、环丙沙星（64.61%，n = 241）、舒巴坦-头孢哌酮（51.21%，n = 191）和阿米卡星（33.78%，n = 126）耐药。此外，在373株分离株中，分别在292株（78.28%）和49株（13.14%）中鉴定出1类和2类整合子，未检测到3类整合子。1类整合子可变区最常见的基因盒阵列是dfrA17-aadA5和dfrA12-orfF-aadA2，而在2类整合子可变区仅检测到一个基因盒阵列（dfrA1-sat2-aadA1）。1类整合子分布于各种生理亚型中，未发现占主导的系统发育群。2类整合子在B21亚型中的存在显著高于其他亚型，且与1类整合子共存。本研究表明，肉鸡产品是多重耐药大肠杆菌的潜在来源，耐药基因可通过侧向基因转移传播。
