斑点叉尾鮰肠败血症病原菌的分离与鉴定

近两年来,一种严重的传染性疾病在广西斑点叉尾鮰养殖业中流行,造成鱼苗100%死亡;成鱼损失也高达30%~80%不等。为确定该病病原,对广西南宁、合浦两地患病斑点叉尾鮰脑、肝脏、脾脏和肾脏组织进行了细菌的分离、鉴定及致病性试验。结果从中分离到两株(NN和HP)G-短杆菌,人工感染试验表明,腹腔注射感染可引起健康斑点叉尾鮰100%死亡,浸泡感染可引起30%~55%死亡,并且感染发病的症状与自然发病症状相似。两株细菌的形态特征、培养特性和生理生化反应指标均与国外报道的鮰爱德华氏菌参考菌株(JCM1680)相同;两株细菌的16S rRNA基因序列与JCM1680菌株16S rRNA基因序列同源性均为99.3%。由此证实,NN和HP两株细菌为致病性鮰爱德华氏菌,其引起的传染性疾病为斑点叉尾鮰肠败血症。

Isolation and identification of causative pathogen for enteric septicemia of catfish (ESC)

A kind of severe infectious disease burst out in cultured industry of catfish in Guangxi in last two years.It caused the death of fry in 100 % and lost 30 %-80 % in the older catfish.To confirm the pathology,the experiments of bacterial isolation of the brain,liver,spleen,kidney from Nanning and Hepu,and identification and manual infection tests of the isolated strains were conducted.Two strains(NN and HP) which were gram negative and short rod were isolated.The results of manual infection test indicated that the health of catfish was death 100 % by i.p.,and 30 %-55 % death rate by immersion infection.The symptoms of manual infected were similar with the natural.All tested items of morphological,cultured,physiological and biochemical characteristics completely matched to all of the reference strain(JCM1680) which has been reported in abroad.The 16S rRNA genes sequence of the isolated strains exhibited 99.3 % similarity to JCM1680 strain.All the results of above experiments suggested NN and HP strains were Edwardsiella ictaluri and could induce the infectious disease of ESC.