Ribosomal DNA sequencing of streptococci: Usefulness in species identification?

Identification of streptococci may be a major challenge. Thirty streptococcal culture collection strains were examined by 16S rDNA sequencing (two fragments of 526 bp and 619 bp, respectively). Among the strains belonging to the pyogenic (β-hemolytic) group of streptococci, a high scorebit and percent sequence identity for best taxon match was present, as was high scorebit and sequence differences to second best taxon match. For the non-β-hemolytic strains (viridans streptococci), many could only convincingly be allocated to the correct group of species. Examining data for the 16S rDNA fragments individually showed similar results as when examining combined sequence data. A more certain taxonomic suggestion was however found, when using the combined data. The data obtained with the primer set BSF8/BSR534 were closest to the suggested best taxon matches for the combined data. Misidentifications were not found.