猪源肠出血性大肠杆菌的分离、鉴定及特性研究

Isolation,identification and characterization of enterohemorrhagic Escherichia coli isolated from swine

目的探讨猪源肠出血性大肠埃希菌病原学特征。方法对所分离的菌株进行生化鉴定、药敏试验,并使用聚合酶链反应(PCR)技术检测毒力基因、耐药基因,同时对致病性的菌株进行外膜蛋白分型、REP-PCR和ERIC-PCR分析。结果从315株大肠杆菌中筛选到山梨醇阴性的EHEC21株,其中含有stx1基因的菌株有4株,含有stx2基因3株,含有eae基因的17株,外膜蛋白分型属于三个型,其中OMP-1型最多,有15株,OMP-2型3株,OMP-3型3株,REP-PCR和ERIC-PCR结果显示这些致病性菌株带型差异性较大,分属于不同的亚群。结论华中地区是养殖业比较发达的地区,而且人均消费猪肉比例也较高,EHEC的存在对人是一种潜在的威胁,应加强监测力度,防止该菌在人群中感染和流行。

To investigate the pathogenic properties of enterohemorrhagic Escherichia coli prevalent in pigs, bacteria were isolated from pigs with diarrhea; isolates were typed with biochemical tests and the antibiotics susceptibility assay was performed in accordance to the routine methods. The PCR assay was used to detect the virulence genes and resistance genes. Meanwhile, the pattern of outer membrane proteins of the pathogenic strains of bacteria was typed and the Entrobacter repetive intergenic consensus （ERIC） and the repetitive element PCR genomic fingerprinting（REP PCR） were used to analyze the correlation of the pathogenicity of Escherichia coli. It was found that 21 sorbitol-negative strains of EHEC were isolated from 315 E. colis, of which 3, 4 and 17 isolates harbored the stx2 ,stx1 and eae gene respectively. The pattern of outer membrane proteins showed three different types, of which 15. 3 and 3 strains were OMP-1, OMP-2 and OMP-3 types respectively. As demonstrated by REP-PCR and ERIC-PCR the band type difference of these pathogenic strains were quite evident and they were belonged to different sub-groups. From these observations, it is apparent that the EHEC infection is a potential threat in central area of China where the proportion of consumption of the pig meat is rather high. So, the surveillance against this infection in these area should be strengthened in order to prevent the transmission and spreading of infection.