Pathological and immunohistochemical findings of naturally infected european sea bass by aeromonas veronii

Objective: This study was carried out to investigate the extent and intensity of the macroscopic, histopathological and immunohistochemical infection in naturally infected sea bass with Aeromonas veronii. Material and Methods: In this study; 22 European sea bass infected with Aeromonas veronii were examined macroscopically, bacteriologically, histopathologically and immunohistochemically. Ziehl-Neelsen and Brown-Hopps stainings were performed in addition to routine HE staining in histopathological examinations. Polyclonal antibody was produced using New Zealand Albino rabbit for immunohistochemistry, and sequence analyzes, API 20E and VITEK-2 analyzes were applied in bacteriological examination. Results: When the sequence data of the obtained bacteria were matched in the gene bank, it was observed that the bacteria showed similarity with Aeromonas veronii at rates varying between 96-98%. Histopathologically, granulomas were the most striking finding. Immunohistochemical data show that bacteria are mostly located in macrophage cytoplasm in granulomas and form new generations in these cells. Conclusions: The inadequacy of necropsy and histopathological findings in the differential diagnosis, and the spread of chemical and molecular methods over a long period of time following bacteriological culture have resulted in delays in diagnosis. Therefore, it was concluded that immunohistochemical methods should be added to the diagnosis. Key words: Aeromonas veronii, Bacteriology, Histopathology, Immunohistochemistry, European Sea Bass