Virulence factors analysis and determination of the suitable chemical agent to inhibit Streptococcus mutans growth and biofilm formation

Abstract

Streptococcus mutans is one of the most important causes of tooth decay and oral diseases, and it has received wide attention from researchers worldwide. The present work aimed to investigate, evaluation and comparisons effect of the antimicrobial and anti-biofilm property of some commercial compounds (chlorhexidine, hyaluronic acid, sodium fluoride and silver nanoparticles) against oral bacteria pathogens of S. mutans. In this work, S. mutans ATCC 25175 was used and its virulence factors were analyzed using Seed Viewer and The Comprehensive Antibiotic Resistance Database (CARD). The antibacterial susceptibility testing (AST) confirms effects of chlorhexidine mouthwash on S. mutans ATCC 25175 beggar than all components. The minimum inhibitory concentration (MIC) minimum bactericidal concentration (MBC) and Minimum biofilm inhibition concentration (MBIC) of the commercial compounds were determined. The statistical analysis was performed using One-Way ANOVA (Tukey test). The VITEK2system was used to confirm the biochemical features of S. mutans ATCC 25175 and susceptibility testing was done to compare the results with Seed Viewer and CARD analysis. The findings showed that The MICs, MBCs, and MBIC means of chlorhexidine against S. mutans ATCC 25175 was 0.0079, 0.0038, and 0.0039 μg/mL respectively, where its biological activity was significantly (P < 0.05) higher compared to other commercial compounds included in this study. The S. mutans strain used in this study showed sensitivity to all tested antibiotics and the Seed Viewer and CARD reported that it has several virulence factors such as adhesion genes (hsp33, Cpa, PrtF, PrtF2, MsmRL, Nra, SOF, LepAL, Spy0135, and RofA) and antibiotic-resistant genes (vanY, vanT, and mdeA). This study concluded that chlorhexidine was the best in inhibiting S. mutans growth as well as preventing biofilm formation, and the study recommends further investigation about antibiotic resistance genes and susceptibility profile.