反刍动物产志贺毒素大肠杆菌的分离鉴定和致病潜力分析

Isolation,identification and pathogenic potential analysis of Shiga toxin-producing Escherichia from ruminants

产志贺毒素大肠杆菌(Shiga toxin-producing Escherichia coli,STEC)是重要的食源性病原,而STEC往往以正常菌群的形式存在于牛羊等反刍动物肠道。【目的】本研究对牛羊粪便样品中的STEC分离和鉴定并对分离株进行致病潜力分析。从江苏、云南和河北等地共分离到羊源STEC菌株11株,牛源STEC菌株1株,另新疆农业大学佟盼盼组馈赠牛源菌株10株。【方法】通过细菌选择培养及特异性基因stx1和stx2的检测进行分离鉴定;并通过Vero细胞毒性试验、溶血活性试验和毒力因子的检测分析STEC分离株的致病潜力。【结果】分离到羊源分离株11株,分离率17.5%(11/63);分离得到牛源分离株1株,分离率0.7%(1/134);11株羊源分离株中有5株对Vero细胞具有强的毒性,3株有溶血活性;11株牛源分离株中有5株对Vero细胞具有强的毒性,3株有溶血活性。11株羊源STEC分离株eae基因携带率为63.6%(7/11),而11株牛源STEC分离株eae基因携带率仅为9.0%(1/11)。【结论】结果表明羊源STEC菌株的分离率和致病潜力高于牛源菌株,所以,除牛外,羊作为STEC菌株宿主也应该得到更多的重视。

Shiga toxin-producing Escherichia coli(STEC)is an important food-borne pathogen,which often exists in the intestines of ruminants,such as cow and sheep,as normal flora.[Objective]In this study,we isolated and identified Shiga toxin-producing Escherichia coli isolates from cow and sheep feces samples,and analyzed their pathogenic potentials Totally 11 Shiga toxin-producing Escherichia coli strains from sheeps and 1 isolate from cattle were isolated from Jiangsu,Yunnan,and Hebei,and another 10 isolates of STEC from cattle were donated by Tong Pan Group of Xinjiang Agricultural University.[Methods]We conducted the separation and identification through bacterial selective culture and detection of specific genes stx1 and stx2.We analyzed the pathogenic potential of the Shiga toxin-producing Escherichia coli isolates by Vero cytotoxicity test,hemolytic activity test,and toxin factor detection.[Results]In this study,the separation and identification result revealed that 11 isolates of sheep origin were isolated with an isolation rate of 17.5%(11/63);1 isolate from cow origin was isolated with an isolation rate of 0.7%(1/134).The pathogenic potential results showed that,among the 11 sheep-derived isolates,5 of them had strong toxicity to Vero cells,and 3 had hemolytic activity.Among the 11 cow-derived isolates,5 had strong toxicity to Vero cells,and 3 had hemolytic activity.The eae gene carrying rate of the 11 sheep-derived Shiga toxin-producing Escherichia coli isolates was 63.6%(7/11),while the eae gene carrying rate of the cow-derived 11 Shiga toxin-producing Escherichia coli isolates was only 9.0%(1/11).[Conclusion]The results indicated that the isolation rate and pathogenic potential of the Shiga toxin-producing Escherichia coli strains derived from sheep were higher than the strains of cow origin.Therefore,sheep,as the host of Shiga toxin-producing Escherichia coli strains,should be paid higher attention than cow.