Subject(s)
Aeromonas salmonicida/pathogenicity , Fish Diseases/microbiology , Fish Diseases/pathology , Gadiformes/microbiology , Gram-Negative Bacterial Infections/veterinary , Aeromonas salmonicida/immunology , Aeromonas salmonicida/physiology , Animals , Bacterial Vaccines , Fish Diseases/prevention & control , Fisheries , Gram-Negative Bacterial Infections/microbiology , Gram-Negative Bacterial Infections/pathology , Gram-Negative Bacterial Infections/prevention & control , Time FactorsABSTRACT
In 7 instances between 2000 and 2003, clinical investigation of populations of fresh- and seawater-reared, vaccinated, Atlantic salmon Salmo salar suffering total losses of between 0.1 and 35 % revealed infection with a Gram-positive rod-shaped bacterium. The isolations were geographically widespread, occurring in both Norway and Scotland. In all cases, a Gram-positive bacterium, subsequently identified as Rhodococcus erythropolis, was isolated in pure culture. Infections, although systemic, were focused within the peritoneal cavity. While initial attempts to reproduce the disease by intraperitoneal injection of unvaccinated Atlantic salmon failed, Koch's postulates were subsequently fulfilled in fish vaccinated with a commercially available oil-adjuvanted vaccine.
Subject(s)
Actinomycetales Infections/veterinary , Bacterial Vaccines/adverse effects , Fish Diseases/microbiology , Rhodococcus/pathogenicity , Salmo salar , Actinomycetales Infections/epidemiology , Actinomycetales Infections/microbiology , Actinomycetales Infections/pathology , Animals , Fish Diseases/epidemiology , Fish Diseases/pathology , Fisheries , Genotype , Peritoneal Cavity/microbiology , Phenotype , Phylogeny , Polymerase Chain Reaction/veterinary , RNA, Ribosomal, 16S/genetics , Rhodococcus/classification , Rhodococcus/isolation & purification , Survival Analysis , Time FactorsABSTRACT
From four separate incidents of disease in farmed Atlantic salmon over a four-year period, gram-negative rod-shaped bacteria were consistently isolated by culture on sea-water blood agar. Biochemical and physiological tests indicated that the organism was related to the family Pasteurellaceae, and this was confirmed from the 16S rRNA gene sequence. Comparison of the 16S rRNA gene sequence with those of 45 members of the Pasteurellaceae showed that the closest phylogenetic relationship was with an organism termed 'Pasteurella phocoenarum', isolated from a porpoise, for which the 16S rRNA gene sequence has been recorded but for which the properties have yet to be published. It is proposed that this bacterium isolated from salmon should be classified as a new species, namely Pasteurella skyensis sp. nov. The type strain of Pasteurella skyensis sp. nov. is strain 95A1T (= NCTC 13204T = NCIMB 13593T).
Subject(s)
Disease Outbreaks , Fish Diseases/epidemiology , Pasteurella Infections/veterinary , Pasteurella/classification , Salmo salar/microbiology , Animals , Aquaculture , Fish Diseases/microbiology , Genes, rRNA , Molecular Sequence Data , Pasteurella/genetics , Pasteurella Infections/epidemiology , Pasteurella Infections/microbiology , Phylogeny , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNAABSTRACT
Plasma lipase concentrations were determined in Atlantic salmon post smolts at weekly intervals on two farms from late June. On one farm there was a significant increase (P < 0.001) in lipase concentration which coincided with a suspicion of pancreas disease on clinical grounds. A definitive diagnosis was subsequently confirmed by histopathology. The exercise was repeated on 10 farms in the following year and the results provided additional evidence of the value of monitoring lipase concentration as an indication of pacreas disease at an earlier stage than it can be detected by clinical signs and histopathology alone.
Subject(s)
Clinical Enzyme Tests/veterinary , Fish Diseases/diagnosis , Lipase/blood , Pancreatic Diseases/veterinary , Salmon , Animals , Fish Diseases/pathology , Pancreatic Diseases/diagnosis , Pancreatic Diseases/pathologyABSTRACT
Sixty-five isolates of Aeromonas salmonicida were assessed for antimicrobial sensitivity by disc diffusion tests and the results compared with the minimum inhibitory concentration for each isolate. The results demonstrated that disc diffusion, using a standard technique, may be used to categorize isolates as sensitive or resistant provided that the corresponding minimum inhibitory concentrations are known.
