RESUMO
Arctic char Salvelinus alpinus farmed in different places in Austria and free of the viral diseases viral haemorrhagic septcaemia (VHS), infectious haematopoietic necrosis (IHN) and infectious pancreatic necrosis (IPN) experienced disease and mortality. Diseased fish showed skin ulceration and pathological signs of sepsis. Aeromonas sp. was isolated as pure culture from the kidney of freshly euthanized diseased fish. Three independent isolates from outbreaks that occurred on 2 of the affected farms were analyzed phylogenetically by DNA sequence analysis of the rrs and gyrB genes and phenotypically with biochemical reactions. All 3 isolates were identified as Aeromonas salmonicida subsp. smithia. Analysis of virulence genes in these isolates revealed the presence of a Type III secretion system as well as several related virulence effector genes including aexT, encoding the Aeromonas exotoxin AexT, aopP and aopH. These genes are characteristic for virulent strains of typical and atypical subspecies of A. salmonicida.
Assuntos
Aeromonas salmonicida/fisiologia , Surtos de Doenças , Doenças dos Peixes/epidemiologia , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Negativas/veterinária , Dermatopatias Bacterianas/veterinária , Truta/microbiologia , Aeromonas salmonicida/classificação , Aeromonas salmonicida/genética , Aeromonas salmonicida/patogenicidade , Animais , Áustria/epidemiologia , Doenças dos Peixes/patologia , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/patologia , Dados de Sequência Molecular , Filogenia , Homologia de Sequência do Ácido Nucleico , Dermatopatias Bacterianas/epidemiologia , Dermatopatias Bacterianas/microbiologia , Dermatopatias Bacterianas/patologia , Especificidade da Espécie , Virulência/genéticaRESUMO
To identify a group of eight Aeromonas strains of our collection showing ribotyping patterns similar to those described for the species Aeromonas popoffii, 16S rRNA gene sequence analysis was performed. Results were in agreement with the DNA binding values, and allowed the identification of a 'signature region' differentiating the A. popoffii strains from all other members of the genus Aeromonas.