一株牛源towneri不动杆菌的分离鉴定

Isolation and identification of a bovine Acinetobacter towneri strain

目的明确四川某肉牛场群发体温升高、高度呼吸困难、流涎等疾病的原因。方法采集患牛鼻腔拭子、血样、病理组织等样品,通过划线法和革兰氏染色进行细菌分离培养、形态学和生化鉴定;通过PCR扩增并测定16s rRNA基因序列,再用MEGA-X软件进行同源性分析、构建进化树,并进行药敏检测。结果分离到一株革兰阴性棒状杆菌,生化特性中动力、氧化酶、硝酸盐还原为阴性,过氧化氢酶为阳性,与不动杆菌属相符合;对目的菌进行RT-PCR扩增,得到1500 bp目的条带,通过Blast分析,16S rRNA序列与GenBank中towneri不动杆菌株的同源性均达99%,命名为ZZC3-9;药敏试验,该菌对亚胺培南、氟苯尼考、阿米卡星、庆大霉素、卡那霉素、强力霉素、多粘菌素B高度敏感,对阿奇霉素、头孢他啶、链霉素、亚胺培南、美罗培南、舒巴坦耐药。结论首次从呼吸道疾病牛分离到towneri不动杆菌,而且能引起肉牛死亡,但该菌对其他动物是否有致病性及人类生活环境的影响有待进一步探讨。

Objective In order to investigate the cause of beef cattle suffering from respiratory syndrome such as fever,high difficulty in breathing and salivate in a cattle farm in Sichuan Province.Methods Samples of Nasal swab,blood and pathological tissue from diseased cattle were collected for bacterial isolation and culture by streaking and Gram staining.and its morphological and biochemical characteristics and 16 SrRNA gene sequence were determined,homology analysis was performed using the software MEGA-X,evolutionary tree was constructed,and drug susceptibility was determined.Results The isolates were gram-negative Corynebacterium,its biochemical characteristics were negative for motivity,oxidase and nitrate reduction,and positive for catalase,which were consistent with acinetobacter genus.RT PCR was used to amplify the target bacteria and 1500 bp target band was obtained.The 16 S rRNA sequence had 99%similarity with A.towneri strain in GenBank.Therefore,the isolates were identified as A.towneri and named ZZC3-9.Drug sensitivity tests indicate that the isolates were highly sensitive to imipenem,fluphenicol,amikacin,gentamicin,kanamycin,doxycycline,polymyxin B,and resistant to azithromycin,ceftazidime,streptomycin,imipenem,meropenem,sulbactam.Conclusion A.towneri was isolated from cattle with respiratory disease for the first time,and it can cause the death of beef cattle.However,the pathogenicity of A.towneri to other animals and the impact of human living environment need to be further discussed.