title: Flavobacterium psychrophilum associated with septicaemia and necrotic myositis in Atlantic salmon Salmo salar: a case report.
abstract: We describe the first case from Norway of increased mortality in Atlantic salmon Salmo salar (L.), with septicaemia and necrotic myositis, associated with infection by Flavobacterium psychrophilum. The outbreak occurred in smolt of 60 to 100 g in fresh water on a land-based farm in Western Norway during winter 2008-2009. The water temperature was < 5 degrees C and the accumulated mortality was 7.0%. Necropsy of dead and moribund fish revealed a swollen dark spleen, pale liver, serohaemorrhagic ascites and haemorrhage in the abdominal fat and muscle. F. psychrophilum was isolated from the kidney and spleen of diseased fish. Muscle biopsy revealed the presence of long filamentous rods in necrotic areas of skeletal muscle. Immunohistochemistry was positive for F. psychrophilum. Identification of cultured isolates as F. psychrophilum was confirmed using phenotypic testing and sequencing of the 16S rRNA gene. Analysis by allele-specific polymerase chain reaction (allele-specific PCR) indicated that 2 different genotypes of the bacterium were present in the outbreak.
authors.affiliation: Norwegian Veterinary Institute Bergen, PO Box 1263 Sentrum, 5811 Bergen, Norway. hanne.nilsen@vetinst.no
authors.forename: Hanne
authors.initials: H
authors.lastname: Nilsen
authors.forename: Renate
authors.initials: R
authors.lastname: Johansen
authors.forename: Duncan John
authors.initials: DJ
authors.lastname: Colquhoun
authors.forename: Inge
authors.initials: I
authors.lastname: Kaada
authors.forename: Kirsten
authors.initials: K
authors.lastname: Bottolfsen
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Vågnes
authors.forename: Anne Berit
authors.initials: AB
authors.lastname: Olsen
mesh_terms: D000818:Animals; D004196:Disease Outbreaks / Q000662:veterinary; D005393:Fish Diseases / Q000453:epidemiology / Q000382:microbiology* / Q000473:pathology; D045826:Flavobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D005417:Flavobacterium / Q000302:isolation & purification*; D009220:Myositis / Q000382:microbiology / Q000662:veterinary*; D009664:Norway / Q000453:epidemiology; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D020317:Salmo salar; D018805:Sepsis / Q000382:microbiology / Q000662:veterinary*
chemical_list: D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S