鲫鳃出血病2种病原菌的分离及鉴定

Isolation and identification of two pathogenic bacteria from Carassius auratus infected with gill hemorrhagic disease

从患有鳃出血病的鲫鳃组织分离出2种革兰氏阴性杆菌,并进行形态特征及16S r RNA基因序列分析。结果显示,这2种病原菌为维氏气单胞菌(Aeromonas veronii)和阴沟肠杆菌(Enterobacter cloacae)。体外溶血试验结果显示,2种菌对鱼的红细胞都有较强的溶血作用,且维氏气单胞菌的溶血速率明显高于阴沟肠杆菌。人工感染试验显示,这2种菌都具有较强的毒力,两者混合感染比单独感染致病率更高;但单独感染时阴沟肠杆菌比维氏气单胞菌引起的鳃出血症状更明显。5种常用水产药的耐药性结果表明两种菌都有一定的耐药性,但是维氏气单胞菌的耐药性更强。

Two Gram-negative pathogenic bacteria were isolated from the Carassius auratus infected with gill hemorrhagic disease.Based on their morphological feature and the results of 16S rRNA sequence,the isolates were identified as Aeromonas veronii and Enterobacter cloacae.E.cloacae is first reported as the pathogenic bacteria of the fish in this study.The vitro hemolysis test showed strains of two pathogenic bacteria had strong hemolysis effects on fish hemocytes.Meanwhile,the hemolysis rate of A.veronii was significantly higher than that of E.cloacae.The test of artificial infected samples indicated that the isolates of two pathogenic bacteria had strong virulence and the pathogenic rate of mixed infection with two bacteria was higher than single infection.Drug resistance tests results of five commonly used aquaculture drugs showed that both of these two bacteria had drug resistance.A.veronii showed stronger drug resistance than E.cloacae.