title: Detection and discrimination of common bovine mastitis-causing streptococci.
abstract: Detection and typing of bovine mastitis pathogens are currently limited by time-consuming and culture-based techniques. In this work, a novel genus-specific DNA marker for Streptococcus and species-specific DNA markers for the prevalent mastitis pathogens Streptococcus agalactiae and Streptococcus uberis were designed and assessed. In order to enable further discrimination of these mastitis-causing streptococci, metabolic and pathogenicity-related genes were used to infer additional functional markers. A total of 12 DNA markers were validated with a set of 50 reference strains and isolates, representative of the Streptococcus genus, of closely related species and of microorganisms with matching habitats. The experimental validation, using dot blot hybridization under high stringency conditions, confirmed the specificity of the selected markers. The broad-spectrum taxonomic marker (ST1) was specific to the Streptococcus genus and the markers selected for S. agalactiae (A1 and A2) and S. uberis (U1 and U2) were shown to be species-specific. The functional markers revealed strain-specific patterns of S. agalactiae and S. uberis. Markers derived from the fructose operon (FO1 and FO3) were specific to bovine isolates of S. agalactiae, and the nisin operon markers (NU1 and NU3) were able to discriminate isolates belonging to S. agalactiae and S. uberis. The virulence-associated markers (V1, V2 and V3) allowed the detection of S. uberis and of closely related species. This work suggests that the combined use of these novel taxa-specific markers coupled with discriminatory functional markers presents a promising approach for the rapid and cost-effective detection and discrimination of common bovine mastitis-causing pathogens, which will contribute to an improved treatment and control of this disease.
authors.affiliation: FCUP - Faculdade de Ciências, Departamento de Biologia, Edifício FC4, Via Panorâmica n° 36, Universidade do Porto, 4150-564 Porto, Portugal.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Almeida
authors.forename: Pedro
authors.initials: P
authors.lastname: Albuquerque
authors.forename: Ricardo
authors.initials: R
authors.lastname: Araujo
authors.forename: Niza
authors.initials: N
authors.lastname: Ribeiro
authors.forename: Fernando
authors.initials: F
authors.lastname: Tavares
mesh_terms: D000818:Animals; D002417:Cattle; D005260:Female; D005819:Genetic Markers / Q000235:genetics; D008414:Mastitis, Bovine / Q000175:diagnosis* / Q000382:microbiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D013291:Streptococcus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D013292:Streptococcus agalactiae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology
chemical_list: D005819:Genetic Markers