Characteristics of an Enterococcus‐like bacterium from Australia and South Africa, pathogenic for rainbow trout, Oncorhynchus mykiss (Walbaum)

Abstract. Severe mortalities of up to 60% have occurred in Australian and South African farmed rainbow trout, Oncorhynchus mykiss (Walbaum), infected with Gram‐positive cocci. Infected fish develop septicaemia and characteristic exophthalmos. Strains collected from outbreaks of disease appear to have attributes of the genus Enterococcus although no Lancefield group D antigen could be detected. All strains grew at 10°C but not at 45°C, grew in 6·5% NaCI, were bile‐aesculin positive and hydrolysed L‐pyrrolidonyl‐β‐naphthylamide. Isolates from both countries have similar phenetic characteristics and whole cell protein profiles.