Liu Ping-Chung, Lin Ji-Yang, Hsiao Pei-Tze, Lee Kuo-Kau
Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan.
J Basic Microbiol. 2004;44(1):23-8. doi: 10.1002/jobm.200310316.
Outbreaks of serious mortality among cultured juvenile cobia Rachycentron canadum L. (weighing 8-10 g) characterized by lethargy, dark skin and ascites in the peritoneal cavity while some fish possessing damaged eyes occurred in July and August of 2001 in Taiwan. Fifteen motile bacterial strains were isolated from head kidney and/or the ascites on tryptic soy agar supplemented with 1% NaCl (TSA1) and/or thiosulphate citrate bile salt (TCBS) sucrose agar plates during the two outbreaks. All the isolates were characterized and identified as Vibrio alginolyticus on the basis of biochemical characteristics, and comparisons with those of the reference strain V. alginolyticus ATCC 17749. The strain C3c01 (a representative of the 15 similar field isolates), was virulent to the cobia with an LD50 value of 3.28 x 10(4) colony forming units/g fish body weight. All the moribund/dead fish exhibited lethargy, dark skin and ascites in the peritoneal cavity as that observed in natural outbreaks. The same bacteria could be reisolated from kidney and the ascites of fish after bacterial challenge using TSA1 and TCBS plates. The results reveal that V. alginolyticus is an infectious agent of vibriosis in the cobia.
2001年7月和8月，台湾养殖的军曹鱼幼鱼（体重8 - 10克）爆发严重死亡事件，病鱼特征为嗜睡、皮肤变黑和腹腔积水，部分鱼眼睛受损。在两次疫情爆发期间，从病鱼的头肾和/或腹水中，在添加1%氯化钠的胰蛋白胨大豆琼脂（TSA1）和/或硫代硫酸盐柠檬酸盐胆盐（TCBS）蔗糖琼脂平板上分离出15株运动性细菌菌株。根据生化特性，并与溶藻弧菌参考菌株ATCC 17749进行比较，对所有分离菌株进行了鉴定，确定为溶藻弧菌。菌株C3c01（15株相似现场分离株的代表）对军曹鱼具有致病性，半数致死剂量（LD50）值为3.28×10⁴菌落形成单位/克鱼体重。所有濒死/死亡的鱼都表现出嗜睡、皮肤变黑和腹腔积水，与自然爆发中观察到的症状相同。使用TSA1和TCBS平板对鱼进行细菌攻击后，可从鱼的肾脏和腹水中再次分离出相同的细菌。结果表明，溶藻弧菌是军曹鱼弧菌病的病原体。
