Pathogenicity of Streptococcus agalactiae Isolated from a Fish Farm in Selangor to Juvenile Red Tilapia (Oreochromis sp.)
Pathogenicity of Streptococcus agalactiae Isolated from a Fish Farm in Selangor to Juvenile Red Tilapia (Oreochromis sp.)
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DOI：
10.3923/javaa.2011.914.919
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发表时间：
2011-01-01
影响因子：
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通讯作者：
Alsaid, Milud
中科院分区：
文献类型：
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作者：
Abuseliana, Ali Farag;Daud, Hassan Hj Mohd;Alsaid, Milud
全球水产养殖业的快速增长暴露了许多在水产养殖领域不为人知的疾病。无乳链球菌（Streptococcus agalactiae）是一种既可感染陆生动物又可感染水生动物的链球菌。在自然疾病爆发中，已从许多鱼类物种中分离出这种生物，并显示对若干鱼类物种具有致病性。最近，少数链球菌病爆发影响养殖红罗非鱼在雪兰莪州进行了调查和S。用无乳链球菌分离物对红罗非鱼幼鱼进行致病性研究。腹腔注射（IP）的幼罗非鱼120 h 50%终点（LD 50）值为1.56 × 10（5）cfu mL（-1）。通过将鱼在含有细菌的水中浸泡30分钟并通过IP注射进行实验感染。观察到IP途径更有效地导致幼红罗非鱼死亡，并在5天内产生明显的临床体征。注意到，接种后5天后死亡率开始降低，鱼在接种后9天后恢复。相比之下，浸泡途径没有诱导死亡，但产生了中度的临床症状，如嗜睡和食欲不振，鱼在6天后开始恢复。根据目前的研究结果，我们可制订适当的措施，以预防及控制日后爆发的疾病。
The rapid increases in global aquaculture industry have exposed many diseases that were not known in aquaculture fields. Streptococcus agalactiae, one of Streptococci species that infecting both terrestrial and aquatic animals. The organisms have been isolated from numerous fish species in natural disease outbreaks and showed to be pathogenic to several fish species. Recently, few streptococcosis outbreaks affecting cultured Red tilapia in Selangor were investigated and the S. agalactiae isolate was used to study its pathogenicity on juvenile Red tilapia. The 120 h 50% endpoint (LD50) value in juvenile tilapia injected Intraperitoneally (IP) was 1.56x10(5) cfu mL(-1). Experimental infections were carried out by bathing the fish for 30 min in water containing the bacteria and by IP injection. It was observed that IP route was more potent to cause mortality to juvenile Red tilapia and produced clear clinical signs within 5 days. It was noted that the mortality started to reduce after 5 days and fish recovered after 9 days post inoculation. In contrast, immersion route did not induce mortality but produced moderate clinical signs such as lethargy and loss of appetite and fish started to recover after 6 days. The findings of the current study would enable us to formulate a suitable measure to prevent and control future disease outbreaks.