An outbreak of Photobacterium damselae subsp damselae infection in cultured silver pomfret Pampus argenteus in Eastern China

In the summer of 2015, a disease outbreak occurred in the Silver pomfret (Pampus argenteus) that reared in indoor tanks of one farm in Eastern China. The primary external sign of affected fish was hemorrhages in fins. In the present study, Gram-negative rods were found in internal organs of diseased fish, and bacterial isolates obtained were identified as Photobacterium damselae subsp. damselae based on phenotypic and genetic analysis. Pathogenicity of one representative P. damselae subsp. damselae isolate was confirmed with experimental infections using healthy silver pomfret. This bacterial isolate also exhibited high cytotoxicity to against a marine finfish kidney cell line. In summary, P. damselae subsp. damselae was the causative agent of the disease outbreak of 2015 in aquacultured sliver pomfret.