非典型致病性大肠埃希菌引起食物中毒病原学研究

目的:对一起食物中毒暴发流行的病原体进行分离鉴定和分子流行病学研究。方法:采集患者和厨工肛拭子、末梢水及物表涂抹拭子共90份。通过分离鉴定、生化试验和血清学试验,确定病原菌后采用实时荧光PCR方法分别检测病原菌毒力基因eaeAi、paHs、tl、ts、tx1与stx2存在情况。其中4株病原菌全基因组经限制性内切酶XbaI酶切后,通过PFGE获得电泳图谱并进行同源性分析。结果:90份标本中22份样品分离出携带eaeA基因的EPEC。BioNumerics分析结果显示4株EPEC PFGE带型完全相同,表明来源于同一克隆株。结论:这起食物中毒是由带eaeA基因非典型EPEC引起的暴发流行。

A study on the etiology of food poisoning caused by atypical enteropathogenic Escherichia coli

Objective:To perform the isolation,identification and molecular epidemiology study of the pathogen in a food poisoning outbreak.Methods: A total of 90 samples from patients′ and kitchen workers′ anal swabs,tap water and object surface swabs were collected.The pathogens were confirmed by bacteria isolation,identification,biochemical tests and serologic tests,then real-time PCR methods were used to detect virulence factors(eaeA,ipaH,st,lt,stx1 and stx2) of pathogens.After the genome of four pathogens was digested by restricted enzyme XbaI,the electrophoresis fingerprint was obtained by PFGE,and homology analysis was performed.Results: EPEC isolates with eaeA gene were present in 22 of 90 specimens.The results analyzed by BioNumerics software showed that the PFGE fingerprints of four isolates were definitely the same,which meant that they came from the same clone.Conclusion: The outbreak of this food poisoning was caused by atypical EPEC carrying eaeA gene.