【摘要】 为明确海南省海口市某养牛场一头黄牛的死亡原因,本研究采集死亡黄牛的脾肺样品进行细菌分离纯化、生理生化鉴定、16S rRNA基因序列分析、药敏试验和小鼠感染试验。结果显示,死亡黄牛脾肺样品在BHI琼脂培养基上形成无色的露珠状优势菌落,镜检为革兰氏阴性杆菌,进一步结合生理生化与细菌16S rRNA基因测序结果确定其为阴沟肠杆菌。该菌对小鼠的半数致死量(LD50)为9.60×10~7cfu/mL,且对死亡小鼠采集病变部位进行细菌分离,得到与原分离菌相同的菌株。药敏结果显示,分离菌对诺氟沙星、氧氟沙星、环丙沙星有较高的敏感性。本研究首次在黄牛中分离得到阴沟肠杆菌,具有重要的意义。为本地区的黄牛养殖业提供疾病防控参考。更多还原

【Abstract】 To investigate the cause of cattle death at a farm in Haikou, Hainan province, the lung and spleen samples were collected for bacterial isolation and purification. Physiological and biochemical identification, 16 S rRNA gene sequence analysis,drug susceptibility andmice infection test were performed. The results showed that colour less, dew-shaped colonies were dominant among those grown on the BHI agar medium, which were identified to be gram-negative bacilli under the microscope. Further physiological, biochemical and 16 S rRNA gene sequencing analysis determined the bacteria as Enterobacter cloacae. The median lethal dose(LD50) of the strain was 9.60×10~7 cfu/mL to mice. The same bacterial strain could be re-isolated from the pathological tissues of the dead mice. The drug susceptibility assay showed that the isolates were highly sensitive to norfloxacin, ofloxacin and ciprofloxacin. Therefore, in this report, we have, for the first time isolated Enterobacter cloacae from yellow cattle, which is of great significance. Our findings would provide a reference for disease prevention and control for local cattle breeding industry.更多还原