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

摘要:

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。

Abstract:

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.