Aeromonas veronii Infection Associated with High Morbidity and Mortality in Farmed European Seabass Dicentrarchus labrax in the Aegean Sea, Greece

In the present study, we examined a disease caused by Aeromonas veronii bv. sobria in sea cage-farmed European seabass Dicentrarchus labrax, in the Aegean Sea, Greece. Commercial sized fish were affected by A. veronii by. sobria and exhibited high morbidity and mortality. Gross pathologic features and histology revealed a systemic infection characterized by the presence of abscesses and chronic granulomatous inflammation. Two clinical bacterial isolates (Aero NS and Aero PDB) were identified as A. veronii by. sobria based on bacteriological characteristics and sequence analysis for 16S rRNA and gyrB genes. Infectivity tests in the form of intraperitoneal injection administration (Aero NS) and immersion in a bacterial suspension (Aero NS and Aero PDB) revealed that both isolates could cause clinical signs similar to those observed in the field and high mortality rate. To our knowledge, this is the first report of A. veronii by. sobria isolated from farmed European seabass in the Mediterranean Sea accompanied by supporting data of its pathogenicity.