食品中大肠杆菌O157∶H7疑似菌株的分离和鉴定研究

Separation and identification of Escherichia coli O157:H7 from food

采集117份食品样品,经过PCR扩增毒力基因stx1、stx2和O157特征基因rfbO157初筛。将部分PCR阳性的食品样品,经过新生霉素EC增菌液增菌、免疫磁珠富集、血清学鉴定、菌落PCR复筛,分离出5株O157:H7疑似菌株。其中1株O157∶H7疑似菌株EC5.11不能与O157诊断血清产生良好凝集反应,采用血清学方法该菌容易漏筛。采用PCR扩增rfbO157基因和H7鞭毛抗原编码基因fliCH7,EC5.11均呈阳性反应。最终包括EC5.11在内的4株疑似菌株被证实为O157∶H7血清型。本研究提出了一种改良方法筛选、鉴定食品中O157∶H7疑似菌株,比起传统方法,减少工作量的同时提高了筛选的特异性。

117 food samples were collected and preliminarily screened by PCR amplification of stx1, stx2 and rfbO157. Then some PCR-positive samples were performed with novobiocin EC broth cultivation, immunomagnetic enrichment, serological identification and colony PCR affination, five suspected E. coli O157：H7 strains were isolated. Among them, strain EC5.11 could not effectively react with O157 diagnosis serum, therefore it could not be isolated from specimens by serological test. EC5.11 showed positive results by using PCR amplification of rfbO157and flagellum antigen encoding genes fliCH7. The four strains including EC5.11 were then identified as O157：H7 serotypes. The paper provided a new method for screening and identifying O157：H7. Compared with traditional methods, the modified method demonstrated could get more effective and accurate results for the isolation and identification of O157：H7 from food samples.