牛源大肠杆菌的分离鉴定与耐药性分析

Isolation,Identification and Drug Resistance Analysis of Bovine Escherichia coli

【目的】新疆某牛场的犊牛发生严重腹泻,出现排血便、黄色水样稀便、精神萎靡、食欲不振等症状。为了确定此次发病的病原做了此实验。【方法】无菌采集了20份犊牛粪便样品,从粪便中分离纯化出1株细菌,并对其进行培养特性观察、PCR鉴定、黏附性基因检测、药敏试验和动物致病性试验。【结果】结果显示分离到了一株革兰氏阴性菌,根据形状和大小判断疑似大肠杆菌;PCR鉴定结果显示为大肠杆菌,分离菌株具有F41黏附性基因。该分离菌株对多黏菌素B、阿米卡星、头孢他啶、头孢哌酮等敏感;在致病性试验中,小鼠在15h内陆续死亡,说明该菌株具有一定致病力。【结论】结果表明,此次牛场犊牛腹泻分离的菌株为产肠毒素性大肠杆菌,携带F41毒力基因,对多黏菌素B、阿米卡星等抗生素敏感,具有一定致病力。

【Objective】Calves in a cattle farm in Xinjiang showed severe diarrhoea with symptoms such as bloody stools,yellow watery stools,depression,and loss of appetite.The aim of the study was to determine the pathogen of this disease.【Methods】Twenty calf faecal samples were collected aseptically,and one bacteria strain was isolated and purified,and was subjected to culture characteristic observation,PCR identification,adhesion gene detection,drug sensitivity test and animal pathogenicity test.【Results】The results showed that a Gram-negative bacterial strain was isolated,and it was suspected to be Escherichia coli according to its shape and size.The results of PCR showed that it was Escherichia coli,and the isolated strain had F41 adhesion gene.The isolated strain was sensitive to polymyxin B,amikacin,ceftazidime and cefoperazone.In the pathogenicity test,the mice died one after another within 15 hours,which indicated that the strain had certain pathogenicity.【Conclusion】The results showed that the strain isolated this time was enterotoxin-producing Escherichia coli,carring F41 virulence gene,and was sensitive to antibiotics such as polymyxin B and amikacin,and had a certain pathogenicity.