1株鸡源奇异变形杆菌的分离鉴定及药敏试验

[目的] 阐明青海省大通县某鸡场病鸡发病原因,为奇异变形杆菌病防控提供参考。[方法] 无菌采集病鸡肝脏、脾脏和泄殖腔拭子等样品,接种普通琼脂和SS琼脂平板进行细菌分离纯化培养,挑取平板上生长的疑似菌落进行革兰染色镜检,再将分离的菌落接种生化鉴定管进行生化鉴定,同时通过PCR扩增16S rDNA和tuf特异性基因并测序。将分离菌接种雏鸡进行致病性试验,采用K-B法评价分离菌对27种抗菌药物的敏感性。[结果] 分离菌为短杆、长杆状多形性杆菌,生化特性与奇异变形杆菌相符。PCR成功扩增出1 400 bp的16S rDNA,序列比对显示与奇异变形杆菌同源性最高,为99.9%。雏鸡致病性试验结果表明,该株奇异变形杆菌对雏鸡有致病性。药敏试验结果显示,该菌株对哌拉西林、头孢吡肟和头孢噻肟等高度敏感,对环丙沙星、奥格门汀中度敏感,对氨苄西林、阿莫西林和头孢唑啉有耐药性,提示该菌对头孢类药物高度敏感。[结论] 分离到的一株奇异变形杆菌对鸡具有较强的致病性,且对多种药物表现出耐药性。

Isolation,Identification and Antimicrobial Susceptibility Test of a Proteus mirabilis Strain from Chicken

[Objective] This study aimed to determine the causative agent of an infectious disease case on a chicken farm in Datong County of Qinghai Province, and to provide reference for prevention and control of Proteus mirabilis infection. [Method] The samples of liver and spleen tissues and cloacal swabs were aseptically collected and inoculated on common nutrient agar and SS agar for bacterial culture, isolation, and purification. Suspected colonies were selected for Gram staining and microscopic examination. The isolated colony were then inoculated into the commercial biochemical reaction test tube for biochemical identification. The isolate was molecularly confirmed by 16S rDNA and tuf specific gene PCR amplification and sequencing. Chicks were challenged with the isolate for pathogenicity test. The K-B method was used to assess the susceptibility of the isolate to 27 antibiotics. [Result] The isolated strain was pleomorphic bacilli （short or long rod-shaped）, and its biochemical traits were consistent with Proteus mirabilis. A 16S rDNA fragment with length of 1 400 bp was successfully amplified by PCR assay, and sequence alignment revealed that it shared the highest homology to Proteus mirabilis at 99.9%. The pathogenicity test demonstrated that the isolate was pathogenic to chicks. The antimicrobial susceptibility test revealed that the isolate was highly sensitive to piperacillin, cefepime and cefotaxime, moderately sensitive to ciprofloxacin and ogmentin, and resistant to ampicillin, amoxicillin and cefazolin. [Conclusion] The strain of Proteus mirabilis isolated from chicken had strong pathogenicity and showed resistance to some antimicrobial agents.