Anginosus group streptococci (AGS) were classified based on the nucleotide sequences of the 16S rRNA gene (16S rDNA) and comprised Streptococcus anginosus, Streptococcus intermedius, and Streptococcus constellatus. It is known that AGS is a causative factor of oral and systematic diseases. The purpose of this study was to discriminate the 56 clinical strains of AGS isolated from Korean oral cavities using phylogenetic analysis of 16S rDNA and species‐specific PCR at the species-level. The 16S rDNA of clinical strains of AGS was sequenced using the dideoxy chain termination method and analyzed using MEGA version 5 software. PCR was performed to identify the clinical strains using species‐specific primers described in previous studies and S. intermedius‐specific PCR primers eveloped in our laboratory. The resulting phylogenetic data showed that the 16S rDNA sequences can delineate the S. anginosus, S. intermedius, and S. constellatus strains even though the 16S rDNA sequence similarity between S. intermedius and S. constellatus is above 98%. The PCR data showed that each speciesspecific PCR primer pair could iscriminate between clinical strains at the species‐level through phylogenetic analysis of 16S rDNA nucleotide sequences. These results suggest that phylogenetic analysis of 16S rDNA and PCR are useful tools for discriminating between AGS strains at the species-level.

• Mi-Hwa Choi(Korean Collection for Oral Microbiology, Department of Oral Biochemistry, and Oral Biology Research Institute, School of Dentistry, Chosun University)
• Soon-Nang Park(Korean Collection for Oral Microbiology, Department of Oral Biochemistry, and Oral Biology Research Institute, School of Dentistry, Chosun University)
• Joong-Ki Kook(Korean Collection for Oral Microbiology, Department of Oral Biochemistry, and Oral Biology Research Institute, School of Dentistry, Chosun University) Correspondence to