草鱼肝胆综合症并发细菌疾病病原分离鉴定及药敏试验

A Pathogen from Grass Carp with Hepatobiliary Syndrome Complicated with Bacterial Disease:Isolation, Identification and Drug Susceptibility Test

对2016年6月江西省鄱阳县高家岭一个养殖场养殖草鱼发生的暴发性疾病进行病原分离鉴定及药敏试验,旨在确定其病因,为今后生产中有效防控该疾病提供参考。利用细菌分离方法在无菌条件下从患肝胆综合症草鱼体内分离、纯化致病菌,通过形态学、生化鉴定和16SrDNA序列分析、gyrB基因序列分析进行菌株鉴定,用攻毒试验找出草鱼的半致死浓度,并采用滤纸片扩散法进行药敏试验。从患肝胆综合症草鱼体内分离、纯化到一株致病菌,经鉴定为维氏气单胞菌,命名为PYG1。攻毒试验表明该菌能感染草鱼,且半致死浓度为1.5×10~4CFU/g鱼体质量。药敏试验结果表明该菌只对氨基糖苷类、第二代和第三代头孢类以及喹诺酮类的氧氟沙星共9种药物表现出敏感或中度敏感,对所测的其他药物耐药,为强耐药菌株。维氏气单胞菌PYG1是引起此次草鱼发病的致病菌,可选用氨基糖苷类、头孢类及喹诺酮类的氧氟沙星等药物进行防治。

The pathogen identification and drug susceptibility test were performed on grass carp(Ctenopharyngodon idellus)that suffered from an acute disease in a fish farm in Gaojialing town,Poyang County,Jiangxi Province in June 2016.The aim was to determine and identify the cause of death and provide reference for effective prevention and control of the disease in future.The pathogenic bacteria were isolated and purified from grass carp with hepatobiliary syndrome by bacterial isolation method under aseptic condition.The morphological,biochemical analysis,16S rDNA sequence analysis and gyrB sequence analysis were used to identify the strains,and the challenge test was conducted to obtain LD50 of grass carp.The drug susceptibility test was conducted by a filter paper diffusion method.The results showed that a pathogenic bacteria strain was isolated from grass carp.The pathogen was identified as Aeromonas veronii,called PYG1.PYG1 could infect grass fish,and the LD50 was 1.5×104 CFU/g.The drug susceptibility test showed that the strain was susceptible or moderately susceptible to 9 kinds of drugs,including aminoglycosides,second-generation and third-generation cephalosporins and ofloxacin,and was resistant to other drugs tested,and was a strongly resistant strain.In conclusion,the pathogen of grass carp is A.veronii PYG1,which could be controlled with aminoglycosides,cephalosporins and quinolones.