Abstract：
1. Shiga toxin-producing Escherichia coli (STEC) strains are associated with disease outbreaks which cause a public health problem. The aim of this study was to determine the frequency of STEC strains, their virulence factors, phylogenetic groups and antimicrobial resistance profiles in broiler chickens.2. A total of 222 E.coli isolates were collected from the caecum of chickens intended to be slaughtered. Antibiotic susceptibility was tested against 21 antimicrobial agents and ESBL phenotype was assessed by double-disk synergy test. The presence of STEC virulence genes stx1, stx2,eaeA and ehxA was detected by PCR. The identification of STEC serogroups was realised by PCR amplification. Additive virulence genes, phylogenetic groups and integrons were examined among the STEC isolates.3. Out of 222 E.coli isolates, 72 (32%) were identified as STEC strains and the most predominant serogroups were O103, O145 and O157. Shiga toxin gene 1 (stx1) was found in 84.7% (61/72) of the STEC strains, and eae and stx2 were detected in 38.8% and 13.8%, respectively. The ESBL phenotype was documented in 48.6% (35/72) of isolates. Most of the isolates (90.3%) carried class 1 integron with the gene cassette encoding resistance to trimethoprim (dfrA) and streptomycin (aadA) in 31.9% of the isolates. Class 2 integron was identified in 36.1% of isolates.4. Broilers can be considered as a reservoir of STEC strains which have high virulence factors and integrons that might be transmitted to other chickens, environments and humans. It is important to undertake surveillance and efficient control measures in slaughterhouses and farms to control measures of STEC bacteria.
摘要：
1.产生志贺毒素的大肠杆菌（STEC）菌株与引起公共卫生问题的疾病爆发有关。这项研究的目的是确定STEC菌株的频率，它们的毒力因子，肉鸡的系统发育群体和抗菌素耐药性概况2.从打算屠宰的鸡的盲肠中收集了总共222个大肠杆菌分离物。针对21种抗菌药物测试了抗生素敏感性，并通过双盘协同试验评估了ESBL表型。PCR检测STEC毒力基因stx1、stx2、eaeA和ehxA的存在。通过PCR扩增实现了STEC血清群的鉴定。加性毒力基因，在STEC隔离物之间检查了系统发育组和整合子。3.在222株大肠杆菌中,72（32％）被鉴定为STEC菌株，最主要的血清群是O103，O145和O157。在84.7%(61/72)的STEC菌株中发现了志贺毒素基因1(stx1),eae和stx2分别检测到38.8%和13.8%，分别。在48.6%(35/72)的分离物中记录了ESBL表型。大多数分离株（90.3％）携带1类整合子，其基因盒编码对甲氧苄啶（dfrA）和链霉素（aadA）的抗性，占31.9％。在36.1％的隔离物中鉴定出2类整合子。4。肉鸡可以被认为是STEC菌株的储库，这些菌株具有高毒力因子和整合子，可能会传播给其他鸡，环境和人类。在屠宰场和农场进行监测和有效的控制措施对STEC细菌的控制措施很重要。
