Streptococcus faecalis as a cause of mortalities among cultured monosex-tilapia.

摘要

During last spring 2005, severe mortalities among cultured monosex tilapia (Oreochromis sp.) were recorded in a private fish farm at Alexandria governorate, Egypt, and caused up to 20% mortality. The isolated bacteria was identified as S. faecalis. Experimental infection was successful through intraperitoneal injection (i.p.). The clinical signs were sluggish movement, respiratory disorder, darkening, loss of scales, uni- or bilateral exophthalmia, haemorrhages of the skin especially in the base of fins and abdominal distension. The common postmortem lesions were congestion of internal organs. The histopathological changes were hydropic degeneration of hepatocytes, depletion of haemopoietic elements and necrosis of kidney tissues. The isolated S. faecalis found to be sensitive to a wide range of antibiotics, and oxytetracycline and amoxicillin were the drugs of choice..