Serotype and distribution of adhesion genes inStreptococcus mutansclinical isolates

Abstract

The delicate balance of the oral cavity is disrupted by hygiene and diet changes, leading to caries. The virulence ofStreptococcus mutans, a key caries pathogen, is partly explained by its rhamnose-glucose polysaccharide (RGP) and its sucrose-dependent and -independent adhesion mechanisms. This study investigates the diversity ofS. mutansthrough analysis of its RGP and the distribution of sucrose-independent adhesion proteins (SpaP, WapA, Cnm, Cbm) in Parkinson’s disease patients.In the PARKIDENT clinical trial, strains were isolated from saliva samples of Parkinson’s patients before and after oral hygiene procedures. Strains were preanalyzed by multiplex PCR for serotype and collagen-binding proteins, followed by high-throughput sequencing and bioinformatics analysis using RAST® and BLAST®. Phylogenetic analyses and protein modeling were also conducted.Of 40 patients in the Parkident clinical trial, only 24 hadStreptococcus mutansstrains isolable from salivary swabs. Serotyping revealed that over 80% of the 44 strains isolated were serotype c, in line with prevalence data in the literature. Furthermore, only SpaP types A and B were identified in the strains. The low variability observed for the WapA protein underlines its functional importance. Finally, thecbmgene was not found in any strain, and only 5 strains possessed thecnmgene, all of them serotype c.The study of these 44Streptococcus mutansstrains showed characteristics similar to other populations. Serotype c predominates, with minimal peptide variability in adhesion proteins (SpaP, WapA). Collagen-binding proteins Cnm and Cbm are rare or absent. Further research is essential for detailed strain distribution in Parkinson’s-affected and general French populations due toS. mutans’growing role in extra-oral pathologies.