食源性致泻大肠杆菌血清型及毒力基因的研究

Study on serotypes and virulence genes of foodborne diarrheogenic Escherichia coli

了解浙江地区食源性致泻大肠杆菌的血清型分布特点及毒力基因携带状况。收集食品安全风险监测点的致泻大肠杆菌分离株,采用玻片凝集法对受试菌株进行血清分型,运用多重PCR检测其携带的毒力基因。在69株受试菌株中,优势血清型包括O148(16株)、O159(11株)、O6(4株)、O15(4株)、O63(4株)和O78(3株),这六种血清型菌株共计42株,占菌株总数的60.9%。菌株主要携带的毒力基因为ast A(42株)、est Ib(25株)、pic(15株)、esc V(14株)、aggR(14株);最常见的毒力基因组合为ast A+est Ib(25株)。进一步分析发现,携带ast A、est Ib基因的O148和O159的菌株对食品安全存在较大威胁。浙江地区食源性致泻大肠菌的类型以EAEC和ETEC为主,携带的主要毒力基因为ast A和est Ib,优势血清型为O148和O159。

The main purpose of the research is to define serotypes and virulence factors of foodborne diarrheogenic Escherichia coli in Zhejiang Province. The distribution characteristics of serotypes and virulence factors of strains collected from food surveillance were detected by serotyping and multiple polymerase chain reaction （PCR）.Of all 69 strains, the most frequent identified serotypes were O148 （ 16 ）, O159 （ 11 ） , 06 （4） , O15 （ 4 ） , 063 （ 4 ） and 078 （ 3 ）, the total number of these serotypes was 42, which accounted for 60.9 % of the strains. And 42,25,15,14,14 strains were positive for astA, estlb, pic, escV, aggR gene, respectively. Among these,25 strains harbored both astA and estlb genes, representing the common type. Furthermore, O148 and O159 strains harboring astA and estlb genes posed a potential threat to food safety.Results showed that EAEC and ETEC harboring asia and estlb genes were the dominant bacteria types, mainly belonging to serotype O148 and O159, among foodborne diarrheogenic Escherichia coli in Zhejiang Province.