Characterization of Bordetella bronchiseptica strains using phenotypic and genotypic markers

Thirty-five strains of Bordetella bronchiseptica, recovered primarily from pigs, rabbits, dogs, cats and humans, were characterized by phenotypic and genotypic markers. Biochemical typing only showed variation in the ability to reduce nitrate to nitrite. OMP profiles from virulent strains showed variations in the region of 85-95kDa, which lead us to describe five OMP-types alpha, beta, gamma, delta and varepsilon. Genotypic markers included the presence of IS1001, and polymorphisms in the flagellin gene (flaA) and pertussis toxin (PT) promoter region. The IS1001 was detected in 16 isolates (2 from humans and 10 from pigs) but was absent in rabbit isolates. The restriction profiles of the flaA gene allowed us to differentiate the strains into types A-C. The PT types were characterized by an RFLP assay and could be typed through patterns III-V. There was no apparent association between the flaA or PT types and the origin of the isolates. Eleven groups of isolates were identified on the basis of specific combinations of the analyzed markers. The combination of phenotypic and genotypic tests used could be useful in characterizing isolates and differentiating between certain clonal types of B. bronchiseptica.