Isolation and Identification of Aeromonashydrophila, Pathogen of Farmed Tilapia (Oreochromisniloticus) in Region Agneby-Tiassa in cote dIvoire

The pathogen responsible of mortality of farmed tilapia fish in region Agneby-Tiassa in Cte dIvoire was investigated. A total of 76 dead fish or showing clinical signs of disease were collected from a private farm in said region. The analyses of samples consisted to isolation of Aeromonas hydrophila, biochemical characterization and molecular detection of virulence gene by PCR. Eleven biotypic profils of A. hydrophila were differentiated in the use or not of lysine decarboxylase, mannitol, rhamnose, gelatin and by fermentation or not of lactose. Biotypes B1 to B4 recorded in the skin, were characterized by positive lysine decarboxylase, positive gelatin, positive mannitol and negative rhamnose. Biotype B10 was showed a negative lysine decarboxylase in the liver of tilapia. Biotypes B5 to B7 of the kidney were differentiated in positive mannitol and positive lysine decarboxylase. The PCR reaction revealed the presence of aerA and hlyA virulence genes in isolated A. hydrophila strains. The biochemical and molecular characterizations allowed to know and to highlight the high virulent of the isolated germ. Hence the interest of the treatment of tilapia production basins against this pathogen.