Detection and Identification of Oral Microorganisms Based on DNA Sequences

Abstract

We developed methods to detect and identify several oral microorganisms directly from dental plaque by polymerase chain reaction (PCR) and DNA hybridization. First, species-specific PCR primers and DNA probes were designed based on the dextranase genes of cariogenic streptoccocal species Streptococcus mutans and Streptococcus sobrinus and an oral normal inhabitant Streptococcus salivarius. Second, PCR primers and DNA probes were designed based on the 16S rRNA gene of Campylobacter rectus, which is associated with periodontal diseases, and Campylobacter showae which is a species related closely to C. rectus. Third, PCR primers were designed based on the 18S rRNA genes of oral protozoan Entamoeba gingivalis and Trichomonas tenax. The PCR primers were specific to the target species, as expected, and could detect DNA as an amount as low as 0.1-1.0 pg or cells as few as 10 to 100. Direct detection from clinical samples was also efficient. Therefore, the present PCR and hybridization could provide simple and rapid detection and identification methods for those oral microorganism species.