兔奇异变形杆菌的分离鉴定及耐药性分析

为了解拉萨市一种兔场种兔腹泻死亡的病因,本试验从一只种兔的肠道内容物中分离出一株细菌,通过革兰氏染色、生化鉴定、16S rRNA PCR扩增和序列比对、动物回归试验及药敏试验进行了分析。结果显示,分离菌株为单个或成对的短杆状的革兰氏阴性菌;分离菌与GenBank中奇异变形杆菌的同源性为73.5%～99.8%,采用Mega 7.0软件将分离菌株与11株参考菌株的16S rRNA序列进行同源性比对分析,并构建系统进化树,综合分析后确定分离菌株为奇异变形杆菌,命名为T2018。在动物回归试验中有3只试验兔出现了腹泻,但均未死亡,剖检结果显示,空肠、回肠肠壁薄而透明,内有半透明胶冻样物;结肠和盲肠黏膜充血,浆膜上有出血斑点。药敏试验显示,分离菌株仅对阿莫西林/克拉维酸、庆大霉素和喹诺酮类的氧氟沙星、环丙沙星、诺氟沙星5种抗菌药表现出高度敏感,对哌拉西林表现为中介,对其他24种抗生素均表现为耐药。上述结果表明该种兔场种兔腹泻死亡的病原为奇异变形杆菌。

Isolation,Identification and Drug Resistance Analysis of Rabbit Proteus mirabilis

In order to understand the cause of diarrhea death in a rabbit field in Lhasa,a strain of bacterium was isolated from the intestinal contents of a rabbit,and was isolated and identified by Gram staining,biochemical identification,16S rRNA PCR amplification and sequence alignment,animal regression test and drug sensitivity test.The results showed that the isolated strain was a single or pair of short rod-shaped Gram-negative bacteria,and the homology of the isolate with Proteus mirabilis in GenBank were 73.5% to 99.8%,the homologous analysis of the 16S rRNA sequence of the isolates and 11 reference strains was carried out by Mega 7.0 software,and the phylogenetic tree was constructed.The isolated strain was identified as Proteus mirabilis,named as T2018.In the animal regression test,there were 3 cases of diarrhea,but none of them died.The results of the necropsy showed that the jejunum and ileum were thin and transparent,with translucent jelly inside;Colon and cecal mucosa were congested,there were bleeding spots on the serosa.Susceptibility tests showed that the isolated strains were only highly sensitive to the five antibacterial agents of amoxicillin/clavulanic acid,gentamicin and ofloxacin,ciprofloxacin and norfloxacin,intermediate to lacillin,and resistant to 24 other antibacterials.The above results indicated that the diarrhea death of rabbits was caused by Proteus mirabilis.