分离病鸡3株大肠埃希菌的鉴定及毒力和细胞毒测定

Isolation,detection, virulence and cytotoxin of three strains of Escherichia coil from diseased chickens

目的 分离病鸡中 3株大肠埃希菌和鉴定其对小鼠的致病力及对Vero细胞毒性作用。方法 将按常规细菌的分离并鉴定的 3株大肠埃希菌 ,接种至昆明系小鼠体内做毒力试验 ,计算死亡率和LD50 (5 0 %致死量 )。采用微量单层细胞培养法测定细菌上清液的细胞毒性作用。结果 分离的 3株细菌生物学性状均符合大肠埃希菌。分离的 3株细菌对小鼠致病率为 10 0 % ;菌量达 6× 10 11CFU/L时死亡率为 10 0 % ;LD50 为 1 5× 10 10 CFU/L。分离的 3株细菌对 2株细胞均无细胞毒性作用。结论 分离的 3株致病性大肠埃希菌与O157∶H7株对小鼠致病力相似 ,可能是潜在的人类的传染源。

Objective To detect and isolate three strains of E.coli in diseased chicken, test their pathogenicity in Kunming mice and cytopathic effect (CPE) in Vero and Hela cells. Methods Detection and isolation of three trains ofE.coli were performed by regular method. Virulent assay was carried out on Kunming mice to test the mortality and LD 50. Supernatant of isolated strains was inoculated in Vero and Hela cells to test the CPE caused by these strains. Results Biologic characteristic of all these three isolated strains was identical to that of EHEC. The isolated strains of 6×10 11 PFU/L caused 100% mortality in Kunming mice. LD 50 was 1.5×10 10 PFU/L. After inoculation of the isolated strains in Vero and Hela cells, no CPE was observed. Conclusion All these three isolated strains have similar pathogenicity with O 157∶H 7 in Kunming mice. They may be a potential pathogens. Attention should be paid to detection of pathogenicE.coli and it is necessary to develop the vaccine against them.