Detection of Tenacibaculum maritimum, the Causative Agent of Tenacibaculosis in Farmed Sea Bass (Dicentrarchus labrax) on the Aegean Sea Coast of Turkey

In this paper we describe the detection of Tenacibaculum maritimum from infected sea bass by using bacteriological, histopathological and molecular methods. These fish were reared in five different floating net cage farms and two hatcheries located in several regions on the Aegean Sea coast of Turkey. We externally observed erythemic and erosive jaw and operculum in infected individuals. Superficial or deep ulcerative skin lesions on head and body surface, gill rot, hemorrhagic and erythemic fins, and slight exophthalmia were also detected. In addition, internal hemorrhage and hyperemia in the visceral organs and bloody fluid in the peritoneal cavity were observed. Bacterial colonies from flat and pale yellow colored individuals were isolated only on Flexibacter maritimus Medium (FMM), Marine Enrichment Cytophaga Agar (MECA) and Marine Agar (MA). They were mostly taken from the kidney and skin lesions of the infected fish and identified as Tenacibaculum maritimum. Vibrio sp. and motile or non-motile aeromonas species were also isolated from most of the infected individuals. Histopathologically, degeneration and liquefactive necrosis in liver, kidney and spleen were observed in the individuals infected with Tenacibaculum maritimum. The identification of Tenacibaculum maritimum was performed directly from the infected fish tissue using nested polymerase chain reaction. In this study, Tenacibaculum maritimum induced mostly mixed infection with Vibrio sp. and motile or non-motile aeromonad species in the four fish farms with 25% mortality. However, this bacterium produced an unmixed infection with the same mortality in young sea bass from only a farm.