新疆牛源多重耐药非O157 STEC产生及传播的分子机制研究

产志贺毒素大肠杆菌（STEC）是一类危害严重的食源性致病菌。O157:H7是STEC中最常见、最重要的血清型，但近年来由非O157 STEC引起的散发感染或暴发逐渐增多，在许多国家或地区甚至超过O157 STEC。人源和动物源STEC均表现多重耐药（MDR），MDR STEC的出现是一个公共卫生问题。牛是STEC的主要宿主，易通过食物感染人类。本研究拟从新疆牛源样品中分离非O157 STEC，通过种系发育背景、血清型、毒力基因、LD50鉴定，评价其毒力特征；通过耐药表型、耐药基因检测，分析其耐药性；对重点研究菌株进行PFGE、MLST和WGS分析，揭示菌株间的亲缘关系，并通过接合试验、Southern杂交和PCR-mapping，在分子水平上验证耐药基因转移机制，阐明MDR非O157 STEC产生和传播的分子机制，为进一步监测和防控STEC基因水平的耐药性传播提供重要的科学依据。

Shiga toxin-producing Escherichia coli (STEC) is a serious type of foodborne pathogens. Although O157: H7 STEC has been regarded as the most predominant and important serotype, sporadic infections or outbreaks caused by non-O157 STEC have been more reported compared to O157 STEC in many countries in recent yesrs. Both human and animal-derived STEC strains have demonstrated multiple drug resistances (MDR), and the emergence of MDR STEC is a public health problem. Cattle are considered to be the primary source of STEC, with contaminated food a major source of STEC human infection. In this study, we intend to compare phylogenetic groups, serogroup, virulence genes and LD50 of isolates and assessing the virulence characteristics of non-O157 STEC from bovine samples in Xinjiang; Investigating antimicrobial resistance phenotypes and resistance genes; We will emply PFGE, MLST and WGS to clarify the genetic relationship among key research strains, we try to verify the transfer mechanism of antibiotic resistance genes at the molecular level through the conjugation test, Southern hybridization and PCR-mapping. To elucidate the molecular mechanism of the generation and transmission of MDR non-O157 STEC and important scientific basis for further monitoring and prevention and control of drug resistance transmission at STEC gene level.