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Bacterial Infection in Cultured Common Dentex (Dentex dentex, L. 1758)
Authors: Tülay AKAYLI, Çiğdem ÜRKÜ, Remziye Eda YARDIMCI, Özgür ÇANAK
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: The aim of this study is the identification of microbial agents recovered from 8 moribund common
dentex (Dentex dentex) samples (140-200 g), determination of their antimicrobial susceptibilities and description
of histopathological changes. Main clinical external and internal symptoms of bacterial haemorrhagic
septicaemia cases such as fin base and liver haemorrhages, splenomegaly, accumulation of fluid in the intestines
and peritoneal cavity were observed. Bacteriological samples of liver, kidney and spleen were streaked onto
Marine Agar and Tryptic Soy Agar plates containing %1,5 NaCl and incubated at 22°C for 48h. Gram-positive
non-motile cocci and Gram-negative motile bacillus were isolated from visceral organs. According to
morphological and biochemical characteristics, isolates were identified as Micrococcus luteus and Vibrio sp. The
Kirby-Bauer disk diffusion method was also performed using multidisc and all isolates were determined to be
sensitive against kanamycin, oxytetracycline and flumequine. In the infected fish, general cell degenerations and
necrosis in various tissues, a remarkable increase in the goblet cells of the intestines, hepatic lipidosis in the liver,
hyperplasia in the gills and the presence of melanomacrophage centres in various tissues were demonstrated. As
a result, here, a mixed infection in moribund fish samples was described and this is the first report on the
histopathological changes of M. luteus infection in a marine fish species. This bacterium was detected as a
possible pathogen of common dentex with various external, internal and histopathological damages.