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对2002年7~9月在广东省阳西县发生大规模死亡的赤点石斑鱼进行病原学研究,现场调查发现养殖赤点石斑鱼平均死亡率高达80%,病鱼的体征为鱼体体表有轻度溃疡,明显的腹部膨胀。解剖发现内脏严重病变,肠坏死,有少量腹水。组织切片观察发现病鱼的心、肝、肠、脾脏中存在大量的细菌,菌体呈现弥漫分布,透亮,个体为球状或短杆状。从以上器官及血液分离到3个优势菌株,分别通过肌肉注射的方法感染健康赤点石斑鱼,筛选出其中毒力较强的1株。用法国梅里埃公司的API20E试剂盒,结合专用电脑软件进行鉴定,确定为普通变形菌(Proteusvulgaris)。用该菌株配制成梯度浓度的菌悬液,再次用肌肉注射的方法对健康赤点石斑鱼进行感染试验,得到其LD50为6.7×104cfu/ml,证实了普通变形菌对赤点石斑鱼具有强毒性,可能是引起这次大规模死亡的致病菌。
The etiological study on the large-scale death grouper in Yangxi County, Guangdong Province from July to September in 2002 showed that the average death rate of the breeding grouper was up to 80%. The diseased fish showed signs of fish Body surface mild ulcers, the obvious abdominal swelling. Anatomy found severe visceral disease, intestinal necrosis, a small amount of ascites. Tissue sections showed that there were a large number of bacteria in the heart, liver, intestine and spleen of diseased fish. The bacteria showed diffuse distribution and translucent, and the individuals were spherical or short rod-shaped. Three predominant strains were isolated from the above organ and blood, respectively. The healthy grouper was infected by intramuscular injection, and 1 strain with stronger virulence was screened out. With French Merial’s API20E kit, combined with special computer software for identification, identified as Proteus vulgaris (Proteusvulgaris). The strain was used to prepare the bacterial suspension with gradient concentration, and then the healthy red spot grouper was inoculated by the method of intramuscular injection to obtain an LD50 of 6.7 × 10 4 cfu / ml, confirming the effect of common proteus on red spot grouper It is highly toxic and may be the causative agent of this massive death.