从暴发性死亡的革胡子鲶(Clarias gariepinus)中分离出可疑病原菌株2010111403(简称1403),分别采用细菌全细胞脂肪酸鉴定系统、Biolog微生物自动鉴定系统及细菌16 S rDNA序列分析三种方法对其鉴定,结果表明菌株1403为嗜水气单胞菌(Aeromonas hydrophila).分离菌株对健康革胡子鲶致病性测试表明其对革胡子鲶的半数致死剂量(LD50)为6.32× 106菌落形成单位(CFU)；实验感染革胡子鲶出现与自然发病相似症状,表明菌株1403是引起革胡子鲶发生暴发性死亡的主要致病病原.药敏试验表明,庆大霉素、四环素、阿奇霉素、氟哌酸、先锋霉素等9种抗生素对分离菌株有较强的抑制作用,但分离菌株对复方新诺明、克林霉素、罗红霉素等4种药物表现出耐药性.%An outbreak of haemorrhagic septicaemia thai caused mass mortality was occurred in cultured Clarias gariepinus in Weifang, Shandong province in November 2010. In order to clarify the cause of the disease, streak plate method was used to isolate the bacteria from moribund fish. Three methods including gas chromatography of cellular fatty acids, biolog microbial identification system and 16 S rDNA sequence analysis were used to identify the isolated pathogen bacteria. Idg, value was used to evaluate the virulence of pathogen by challenge tests on C. Gariepinus. The antimicrobial susceptibility testing was performed by disc diffusion method. A bacterial strain recovered from diseased C. Gariepinus numbered 2010111403(hereinafter referred to as 1403)was dominant. Identification results by three methods all showed that bacterium 1403 was Aeronwnas hydrophila. Challenge tests demonstrated bacterium 1403 was a virulent strain to C. Gariepinus with Ldjo approximate 6.32 x 10° CFU, with the similar symptoms as the naturally infected fish with haemorrhagic septicaemia. Antimicrobial susceptibility showed that bacterium 1403 were sensitive to 9 kinds of antibiotics such as gentamy-cin, minocycline, azithromycin, norfloxacin, cephalothin, etc, while it is resistant to 4 kinds of antibiotics including Sulfamethoiazolura-trimethoprimum, Clindamycin, Roxithromycin, ext
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