竹鼠源绿色气球菌和大肠杆菌的分离鉴定及致病分析

Isolation,identification and pathogenic analysis of pathogenic Aerococcus viridans and pathogenic Escherichia coli from Rhizomys sinensis

从贵州省某竹鼠养殖场送检的6只患病竹鼠的不同组织病料中分别分离到两种不同的细菌,经细菌形态观察、生化试验鉴定、16S rDNA基因序列分析,确定两株分离菌一株为大肠杆菌,命名为GZ-QDN1;另一菌株为绿色气球菌,命名为GZ-QDN2。药敏试验结果显示,分离菌株GZ-QDN1对头孢曲松、头孢拉啶、复方新诺明等9种药物有较强的敏感性,分离菌株GZ-QDN2对恩诺沙星、多黏菌素B、新霉素等10种药物有较强的敏感性。动物回归试验结果显示,分离菌GZ-QDN1和GZ-QDN2具有较强的致病性,对竹鼠的半数致死量LD_(50)分别为1.45×10^(6)CFU/m L和1.75×10^(6)CFU/m L。组织病理学观察显示,死亡竹鼠心脏、肾和肺等发生了细胞排列较疏松、出血、粒细胞浸润等病理变化。本研究从竹鼠体内分离到致病性大肠杆菌和绿色气球菌各1株,为该竹鼠养殖场查明了主要病因并为细菌性疫病的防治提供了用药参考。

Two strains of bacteria were isolated from different tissues of 6 diseased Rhizomys sinensis from a Rhizomys sinensis farm in Guizhou.By combining bacterial morphology,biochemical test,and identification observations with the results of 16 S r DNA gene sequence analysis,one isolated strain was identified as Escherichia coli,named GZ-QDN1,and the other as Aerococcus viridans,named GZ-QDN2.Drug sensitivity test showed that the isolated GZ-QDN1 strain was highly sensitive to nine drugs,including ceftriaxone,cephradine,and compound sulfamethoxazole,while GZ-QDN2 was highly sensitive to ten drugs,such as enrofloxacin,polymyxin B,and neomycin.Animal regression experiment demonstrated that GZ-QDN1 and GZ-QDN2 had strong pathogenicity,and their median lethal dosages(LD_(50))to Rhizomys sinensis were 1.45×10^(6)CFU/m L and 1.75×10^(6)CFU/m L,respectively.Histopathological observation revealed pathological changes in the hearts,kidneys,and lungs of the dead Rhizomys sinensis,which included loose cell arrangement,hemorrhage,and granulocyte infiltration.To conclude,this study isolated a strain each of the pathogenic Escherichia coli and Aerococcus viridans from the Rhizomys sinensis samples,with the view to identifying the main cause of disease and providing medication references for the prevention and control of bacterial diseases in this Rhizomys sinensis farm.