Isolation of Shewanella putrefaciens from cultured european sea bass, (Dicentrarchus labrax) In Turkey

Abstract

This study describes the etiological agent that caused mortalities on cultured European sea bass, Dicentrarchus labrax, L., in Turkey. The sick fish showed lethargy, loss of appetite, exophthalmus, and ulcers over the dorsal part of the body. Internally, liver haemorrhages, spleen enlargement (splenomegaly) were observed. The spleen, liver and kidney were pale. Ascites in the abdominal cavity was also observed. Gram-negative, cytochrome oxidase and catalase positive and H(2)S producing rods were isolated from skin ulcers, kidney, spleen, liver and blood and identified as Shewanella putrefaciens by using both standard methods and API 20 E test system. Histological examination of sea bass naturally infected with S. putrefaciens indicated depletion of white and red pulpas and deposition of haemosiderin in the melanomacrophage centres in the spleen. The kidney was severely affected, displaying necrosis in renal tubules. Intestinal mucosa membrane sloughed into the lumens. There were vacuole degeneration. necrotic areas in the fatty liver tissue.