点带石斑鱼致病性哈维氏弧菌的分离鉴定及药敏试验

Isolation,identification and antibiotic susceptibility analysis of the pathogenic Vibrio harveyi from Epinephelus coioides

为探究养殖点带石斑鱼死亡原因,从患病点带石斑鱼(Epinephelus coioides)肝脏中分离得到一株细菌,命名为SBY-G。经形态学观察、生理生化试验鉴定,初步判定为哈维氏弧菌(Vibrio harveyi)。16S rDNA基因序列分析显示,菌株SBY-G与哈维氏弧菌菌株(KU364055.1)相似性最高,gapA基因序列分析显示,菌株SBY-G与哈维氏弧菌菌株(LC370081.1)相似性最高,系统发育树显示与哈维氏弧菌聚为一支,因此确定该菌为哈维氏弧菌(Vibrio harveyi)。药敏试验结果表明,菌株SBY-G对阿莫西林、头孢孟多、头孢克肟、头孢曲松、诺氟沙星等15种抗生素高度敏感;对头孢噻肟、庆大霉素、卡那霉素等6种抗生素中度敏感;对氨苄西林、苯唑西林、头孢呋辛、头孢他啶、链霉素、新霉素等18种抗生素不敏感。人工回归感染试验结果显示,菌株SBY-G对斑马鱼的半数致死量LD_(50)为1×10^(5)cfu/g。本研究结果为哈维氏弧菌感染引起鱼类疾病的防治和诊断提供了科学参考。

To explore the cause of death of Epinephelus coioides,a bacterial strain was isolated from the liver of diseased Epinephelus coioides and named as SBY-G.This bacterial strain was preliminarily determined as Vibrio harveyi according to its morphological,physiological and biochemical characteristics.The sequence analysis of the 16 S rDNA and gapA genes respectively showed SBY-G had the highest similarity with V.harveyi(KU364055.1)and(LC370081.1),and the phylogenic trees showed that it was clustered with V.harveyi.The results of antibiotic susceptibility analysis showed that SBY-G was highly sensitive to amoxicillin,cefixime,cefamandole,ceftriaxone,norfloxacin and other fifteen antibiotics,moderate sensitive to cefotaxime,gentamicin,kanamycin and other six antibiotics,while resistant to ampicillin,oxacillin,cefuroxime,ceftazidime,streptomycin,neomycin and other eighteen antibiotics.Artificial infection experiments showed that the median lethal dosage(LD_(50))of the SBY-G strain on zebra fish was calculated as 1×10^(5)cfu/g.The results of this study provide a scientific reference for the prevention,treatment and diagnosis of fish diseases caused by V.harveyi.