花斑副沙鳅源致病性维氏气单胞菌的分离、鉴定及药物敏感性分析

Isolation, identification and drug sensitivity analysis of pathogenic Aeromonas veronii from diseased Parabotia fasciata Dabry

为了对引起养殖花斑副沙鳅(Parabotia fasciata Dabry)幼鳅死亡的分离菌株(XQS1)进行鉴定,本研究对其进行了生理生化分析、16S rRNA基因和gyr B基因序列测定及系统进化树分析。结果显示,该致病菌与维氏气单胞菌(Aeromonas veronii)形态特征以及生理生化特性相似,通过对其16S rRNA基因和gyr B基因序列比对及进化树分析,显示该菌株与GenBank中维氏气单胞菌相关基因序列的一致性均在98%以上,而且在系统进化树中与维氏气单胞菌聚为一簇,综合以上结果确定该致病菌为维氏气单胞菌。溶血性分析和毒力基因检测结果显示,菌株XQS1能够使兔血平板呈β溶血,并携带了act、alt、aer、hlyA毒力基因,进一步证实了该菌株具有较强的致病性。药敏结果显示,该菌株对多西环素、诺氟沙星、氧氟沙星、氟苯尼考等药物敏感,而对其它药物中度敏感或耐药。本研究首次报道了维氏气单胞菌对人工养殖花斑副沙鳅的危害,并为临床上该病的防治提供了药物参考,对花斑副沙鳅产业化养殖具有重要意义。

A bacterium(XQS1)was isolated from the diseased Parabotia fasciata Dabry.In order to identify the species of the strain,we performed physiological and biochemical analysis,16 S rRNA gene and gyr B gene sequencing and phylogenetic tree analysis of XQS1.The results showed that the isolate has similar morphological features and physiological biochemical properties to the Aeromonas veronii.The sequences of 16 S r RNA gene and gyr B gene of the isolate were more than 98%similar to that of A.veronii,and it was clustered in the same branch with A.veronii.The above results confirmed that the disease of P.fasciata Dabry was caused by A.veronii.The hemolysis and virulence genes of XQS1 were tested.The results of hemolysis analysis and virulence gene test showed that strain XQS1 could produce beta hemolysis on rabbit blood platelet,and carried four virulence genes,namely,act,alt,aer and hly A,which further indicated that strain XQS1 had strong pathogenicity.We analyzed the sensitivity of the strain to17 antibiotics in this study to quickly screen out effective drugs.The results indicated that the XQS1 is sensitive to doxycycline,norfloxacin,ofloxacin,florfenicol,and moderately sensitive or resistant to other antibiotics.This study firstly reported the pathogenicity and preventive drugs for treatment of A.veronii on cultured P.fasciata Dabry,and provided a theoretical reference for the prevention and treatment of this disease in the process of P.fasciata Dabry industrialization.