title: Genotyping of Streptococcus dysgalactiae strains isolated from Nile tilapia, Oreochromis niloticus (L.).
abstract: Streptococcus dysgalactiae is an emerging fish pathogen that is responsible for outbreaks of disease on fish farms around the world. Recently, this bacterium was associated with an outbreak at a Nile tilapia, Oreochromis niloticus (L.), farm in Brazil. The aim of this study was to evaluate the genetic diversity, best genotyping method and aspects of molecular epidemiology of S. dysgalactiae infections in Nile tilapia farms in Brazil. Twenty-one isolates from four farms located in different Brazilian states were characterized genetically using pulsed-field gel electrophoresis (PFGE), ERIC-PCR, REP-PCR and sodA gene sequencing. The discriminatory power of the different typing methods was compared using Simpson's index of diversity. Identical sodA gene sequences were obtained from all isolates, and ERIC-PCR and REP-PCR were unable to discriminate among the isolates. PFGE typing detected three different genetic patterns between the 21 strains evaluated; thus, it was the best genotyping method for use with this pathogen. The strains from Ceará State were genetically divergent from those from Alagoas State. The S. dysgalactiae isolates analysed in this study constituted a genetically diverse population with a clear association between geographical origin and genotype.
authors.affiliation: AQUAVET, Laboratory of Aquatic Animal Diseases, Veterinary School, Federal University of Minas Gerais ("Universidade Federal de Minas Gerais"), Belo Horizonte, MG, Brazil.
authors.forename: F A A
authors.initials: FA
authors.lastname: Costa
authors.forename: C A G
authors.initials: CA
authors.lastname: Leal
authors.forename: R C
authors.initials: RC
authors.lastname: Leite
authors.forename: H C P
authors.initials: HC
authors.lastname: Figueiredo
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D023681:Cichlids; D016521:Electrophoresis, Gel, Pulsed-Field / Q000662:veterinary; D005393:Fish Diseases / Q000382:microbiology*; D014644:Genetic Variation; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000662:veterinary; D017422:Sequence Analysis, DNA / Q000662:veterinary; D013290:Streptococcal Infections / Q000382:microbiology / Q000662:veterinary*; D013291:Streptococcus / Q000235:genetics* / Q000302:isolation & purification; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D013482:Superoxide Dismutase
keywords: Brazil; Streptococcus dysgalactiae; molecular epidemiology; pulsed-field gel electrophoresis