IDENTIFICATION AND PARTIAL CHARACTERIZATION OF STREPTOCOCCUS MUTANS ISOLATED FROM VIETNAMESE PATIENTS

Abstract

Dental caries is nowadays one of the most common diseases of the world, especially in developing countries including Vietnam. Streptococcus mutans is considered to be the main pathogen of dental caries because of their high acidogenicity and acidurance. From the samples collected from Vietnamese patients of dental caries, by using selective media of Mitis salivarius and tryptic soy agar at pH 5 and API20 Strep kit we isolated and identified 6 strains of  Streptococcus which were designated as Streptococcus sp. HI, H2, H3, H4, H5 and H6. Three of the 6 strains were shown to have the same banding patterns of the PCR-amplified products of the gene coding for 16S rRNA, followed by restriction enzyme digestion with HaeIll and Hpall (PCR-RFLP) as S. mutans GS-5. Similarly, the three strains were also found to have the 1.3 kb band of dextranase of Streptococcus mulam by using peR with dextranase-specific primers. The obtained results indicated that all the three isolated strains Streptococcus sp. H 1, H2, H3 belong to Streptococcus mutans. By using pH drop and acid killing assays, all the three S. mutans strains were found to be as acidogenic and aciduri as S. mutans GS-S.