竹鼠源棒状杆菌分离鉴定及致病性分析

Isolation and identification of Corynebacterium from bamboo rats (Rhizomys sinensis) and its pathogenesis analysis

从病死竹鼠体内分离到1株细菌,通过形态学观察、生化试验鉴定、16S rDNA基因测序分析及系统进化树构建等方法对分离菌种属进行确定,并采用纸片扩散法进行药敏试验,PCR方法检测耐药基因和毒力基因,人工感染小鼠试验确定分离菌的致病力。病原鉴定显示,分离菌为革兰阳性杆菌,16S rDNA基因测序及BLAST比对显示其与棒状杆菌序列相似度达92.1%~99.2%,结合生理生化鉴定结果确定分离菌为棒状杆菌;药敏试验显示,该分离菌对氟苯尼考、头孢氨苄和青霉素等药物敏感,对复方新诺明、四环素和红霉素等药物表现耐药,耐药基因检测结果显示为oqxB、tetX、sul1和ermF阳性,与药敏试验表型一致;该菌对小鼠有致病性,毒力基因检测发现,分离菌携带fyuA和papA。本研究为竹鼠棒状杆菌病预防及合理用药提供依据。

This experiment was to isolate and identify pathogenic bacteria from sick bamboo rats(Rhizomys sinensis)and to analyze the drug resistance of the isolated bacteria.Four strains of the same bacterium were isolated from dead Rhizomys sinensis.Then,morphological observation,biochemical test,16 S rDNA gene sequencing analysis and phylogenetic tree construction were performed to determine the species of the isolated bacteria,and the paper diffusion method was used to test their drug sensitivity.PCR was used to detect their drug resistance genes and virulence genes,and artificial infection of mice with the virus was performed to determine the pathogenicity of isolates.Pathogen identification showed that the isolate was Gram-positive bacillus.16 S rDNA gene sequencing and BLAST comparison showed that its sequence similarity to Corynebacterium was 92.1%-99.2%.Combined with the results of physiological and biochemical identification,the isolate was identified as Corynebacterium;and drug sensitivity test showed that the isolate was sensitive to such drugs as florfenicol,cephalexin and penicillin,and and was resistant to such drugs as co-trimoxazole,tetracycline and erythromycin.The detection results of drug resistance genes showed that the isolates were oqxB,tetX,sul1 and ermF positive,which was consistent with the phenotype of the drug sensitivity test.The bacterium was pathogenic to mice,and the virulence gene test showed that the isolates carried fyuA and papA.This study provided a basis for prevention and rational treatment of Corynebacterium infection in Rhizomys sinensis.