蓝鳃太阳鱼诺卡氏菌的分离鉴定及药敏分析

为探明患结节病蓝鳃太阳鱼的病因,从蓝鳃太阳鱼(Lepomis macrochirus)脾脏结节处分离获得一病原菌SD1810。通过菌落形态、细菌生理生化鉴定和16S rRNA基因序列分析,确定所得菌株为鰤鱼诺卡氏菌(Nocardia seriolae)。人工回归感染试验结果显示,注射浓度为2.8×107 CFU/mL的菌液能使蓝鳃太阳鱼患病致死,发病症状与原感染鱼相似。从死亡太阳鱼体内可重新分离到与SD1810形态特征、生理生化指标相一致的病菌。对分离获得的鰤鱼诺卡氏菌进行药敏试验分析,结果表明,鰤鱼诺卡氏菌SD1810对红霉素、利福平、庆大霉素、氯霉素、阿米卡星、氟苯尼考等10种抗生素极其敏感,对头孢唑啉,诺氟沙星,青霉素、氨苄青霉素和阿莫西林等6种抗生素具有耐药性。

Isolation,identification and drug sensitive analysis of Nocardia seriolae from diseased Lepomis macrochirus

A strain of bacterium named SD1810 was isolated from Lepomis macrochirus with sarcoidosis,which was identified as Nocardia seriolae by means of gram stain,physiological and biochemical identification,sequencing of 16S rRNA gene and phylogenetic analysis.Artificial infection proved that N.seriolae could kill the bluegill sunfish at the concentration of 2.8×107 CFU/mL and symptoms were similar to those natural cases.N.seriolae could be re-isolated from dead sunfish.Therefore,N.seriolae was the pathogen of bluegill sunfish sarcoidosis.The antibiotic sensitivity test showed that SD1810 was highly susceptible to 10 kinds of drugs including erythromycin,rifampicin,gentamicin,chloral phenicol,amikacin,florfenicol,etc.N.seriolae wasintermediately susceptible to furazolidone and enrofloxacin,but resistance to gefamezin,norfloxacin,G penicillin G,and ampicillin,etc.