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Outbreaks of severe myositis in cultured white sturgeon ( Acipenser transmontanus L.) associated with Streptococcus iniae
Author(s) -
Pierezan Felipe,
Shahin Khalid,
Heckman Taylor I.,
Ang June,
Byrne Barbara A.,
Soto Esteban
Publication year - 2020
Publication title -
journal of fish diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 85
eISSN - 1365-2761
pISSN - 0140-7775
DOI - 10.1111/jfd.13145
Subject(s) - streptococcus iniae , biology , dermis , outbreak , sturgeon , anatomy , microbiology and biotechnology , pathology , virology , fishery , fish <actinopterygii> , medicine
Outbreaks of an infectious disease affecting cultured white sturgeon ( Acipenser transmontanus) were investigated. Clinical signs included erratic swimming, arching of the back and mortality. Necropsy findings included poorly demarcated yellow to dark‐red and friable lesions in the epaxial muscle, ulcerative skin lesions and haemorrhages in the swim bladder and coelomic wall. Histological evaluation revealed areas of necrotizing and heterophilic myositis with aggregates of bacterial cocci. The lumen of blood vessels in the dermis, under ulcerated areas, and in the posterior kidney, was occluded by fibrin thrombi. Aggregates of Gram‐positive cocci were observed in the muscle lesions and within the fibrin thrombi in the dermis and kidney. Genetically homogeneous Streptococcus iniae strains were recovered from affected fish from different outbreaks. The isolates shared high degree of similarity at gene locus ( gyrB ) with previously characterized S. iniae from cultured fish in California, confirming the emergence of this particular strain of S. iniae in US aquaculture.