Authors: Otake S, Hirasawa M, Brown TA, Kawabata Y, Kiyono H, Michalek SM, McGhee JR, Shiota T.

Summary: A mutant of Streptococcus mutans 6715 HSR, which is defective in serotype antigen and designated C307, was shown to exhibit full virulence on buccal, sulcal, and proximal surfaces similar to that of 6715 HSR. In addition, this bacterium caused significant decay on the lingual surfaces. Its colonial morphology and certain biochemical activities which may be related to caries production were distinct from those of 6715 HSR.

This mutant adsorbed to saliva-treated hydroxyapatite beads in greater amounts and aggregated in the presence of either sucrose or dextran in excess of that seen with the parent strain. The abilities of C307 to grow and to produce acid from sucrose and to adhere to glass surfaces were similar to that of 6715 HSR. Although revertants of C307 exhibited biological activities and a content of serotype g antigen similar to that of 6715 HSR, the virulence pattern was still unlike the parent strain. These results suggest that the serotype g antigen is not required for the adherence of cells to smooth surfaces or for caries formation and that the loss of this antigen may alter the surface of cells causing enhanced ability of the cells to aggregate and to adsorb to saliva-treated hydroxyapatite beads.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=6452413&query_hl=28

Authors: Hamada S, Koga T, Ooshima T.

Summary: Streptococcus mutans possesses the abilities to adhere to pellicle-coated tooth surfaces and to form acids - two characteristics associated with the cariogenicity of this micro-organism. De novo synthesis of insoluble glucan by S. mutans glucosyltransferase from sucrose is essential in the adherence process. Therefore, agents which interfere with the adherence ability of S. mutans would be useful for controlling dental caries. In the present report, we have summarized our recent findings concerning virulence factors of S. mutans and means for prevention of S. mutans-induced dental caries.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=6230378&query_hl=5

Author: Banas JA.

Institution: Center for Immunology and Microbial Disease, Albany Medical College,MC-151, 47 New Scotland Avenue, Albany, NY 12208, USA. BanasJ@mail.amc.edu

Summary: Streptococcus mutans is considered one of the primary causative agents of dental caries and can also be a source of infective endocarditis. The main virulence factors associated with cariogenicity include adhesion, acidogenicity, and acid tolerance. Each of these properties works coordinately to alter dental plaque ecology.

The ecological changes are characterized by increased proportions of S. mutans and other species that are similarly acidogenic and aciduric. The selection for a cariogenic flora increases the magnitude of the drop in pH following the fermentation of available carbohydrate and increases the probability of enamel demineralization. This review focuses on the bacterial components that contribute to each of the major virulence properties.

Further understanding of how these components work together in the development of dental caries will be aided by the recent completion of the sequence of the S. mutans genome and experimental designs that model the dental plaque biofilm.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=14977543&query_hl=3