致泻大肠埃希氏菌检验用标准菌株的研究

Study of standard strain for testing diarrheagenic Escherichia coli

对7株大肠埃希氏菌(Escherichia coli)进行分类学鉴定及毒力基因验证,评价其作为GB 4789.6—2016《食品微生物学检验致泻大肠埃希氏菌检验》标准菌株的可行性。采用细菌多相分类学鉴定方法对7株E.coli进行菌种鉴定,根据GB 4789.6—2016标准方法对7株菌进行致泻大肠埃希氏菌相关毒力基因PCR进行确认试验。结果表明,菌株CICC 10003携带uidA基因,CICC 10667携带uidA、sth、lt基因,CICC 10670和CICC 24187携带uidA、escV、stx 1、stx 2基因,CICC 24186携带uidA、pic、astA、aggR基因,CICC 24188携带uidA、invE基因,CICC 24189携带uidA、bfpB、escV基因。CICC 10667、CICC 24186、CICC 24188、CICC 24189分别属于产肠毒素大肠埃希氏菌、肠道集聚性大肠埃希氏菌、肠道侵袭性大肠埃希氏菌、肠道致病性大肠埃希氏菌,CICC 10670和CICC 24187属于肠道出血性大肠埃希氏菌,CICC 10003为非致泻大肠埃希氏菌。7株菌毒力基因检测结果均满足GB 4789.6—2016标准中相应E.coli类别性能要求,可作为致泻大肠埃希氏菌检验用标准菌株。

Taxonomic identification and virulence gene verification of 7 Escherichia coli strains were carried out,and the feasibility of using them as the standard strains of GB 4789.6—2016“Microbiological examination of food—Examination of diarrheogenic E.coli”was evaluated.Seven strains of E.coli were identified by polyphase-taxonomy identification method;according to the methods of GB 4789.6—2016 standard,virulence gene verification of 7 strains of E.coli were carried out.Results showed that the strain CICC 10003 carried gene uidA;CICC 10667 carried genes uidA,sth and lt;CICC 10670 and CICC 24187 carried genes uidA,escV,stx 1 and stx 2;CICC 24186 carried genes uidA,pic,astA and aggR;CICC 24188 carried genes uidA and invE;CICC 24189 carried genes uidA,bfpB and escV.The strains CICC 10667,CICC 24186,CICC 24188 and CICC 24189 were identified as enterotoxigenic E.coli(ETEC),enteroaggregative E.coli(EAEC),enterotoxigenic E.coli(EIEC)and enteropathogenic E.coli(EPEC),respectively;CICC 10670 and CICC 24187 belonged to enterohemorrhagic E.coli(EHEC);CICC 10003 belonged to non-diarrheogenic E.coli.The performance of the 7 strains met the requirements of the corresponding types of E.coli in the GB 4789.6—2016 standard,and they can be used as standard strains for the examination of diarrheogenic E.coli.