Identification of oral mitis group streptococci by arbitrarily primed polymerase chain reaction

"Mitis group" streptococci are commensal but may play some role in dental caries, septicemia or endocarditis. Rapid genotypic identification would aid studies of dental plaque ecology, or diagnostic use. AP-PCR with 58 unpaired arbitrary primers was used to characterize 7 Streptococcus gordonii, 11 Streptococcus sanguis, 2 Streptococcus crista, 5 Streptococcus parasanguis, 18 Streptococcus oralis, and 36 Streptococcus mitis (22 biovar 1 and 14 biovar 2). S. parasanguis 16S rRNA variable region primer RR2 produced species-specific bands with all S. gordonii and S. sanguis. Human V beta 1 T-cell receptor primer 434 yielded concordant genotypic identification of all phenotypically defined S. crista and S. parasanguis, 83% of S. oralis, and 74% of S. mitis biovar 1. Amplicon patterns for S. mitis biovar 2 were heterogeneous. Findings suggest that primers RR2 and 434 in succession will allow rapid identification of genotypic groups corresponding closely to mitis group species established by phenotype.