Red drum Sciaenops ocellatus mortalities associated with Streptococcus iniae infection

We isolated for the first time Streptococcus iniae strains associated with diseased marine fish. Diseased red drum Sciaenops ocellatus were lethargic, and presented external signs (exophthalmia and loss of orientation) resemb ling those of freshwater fish infected by S, iniae. Skin lesions, extending to a necrotizing myositis, were typical of S, iniae infection of red drum. Histopathological findings indicate that S, iniae infection in red drum pr oduces a chronic disease with systemic involvement characterized by multipl e necrotic foci. Molecular epidemiology (RFLP [restriction fragment length polymorphism] ribotyping) revealed that 2 different ribotypes were involved in a single outbreak. The first is the EcoRI 'Israeli' trout and tilapine ribotype (Hind III type a strains), while the second is the EcoRI 'American ' ribotype (Hind III type b strains), typical of tilapines farmed in Texas and Idaho.