In vitro antimicrobial activity of selected mouthwashes on Streptococcus species isolated from adult patients with dental caries

Objective: Dental caries is a preventable oral disease with economic burdens and effects on the quality of life. The study aimed to isolate Streptococcus species implicated in dental caries and also evaluate the antimicrobial potential of three brands of mouthwashes. Methodology: This was a cross-sectional study of patients with active dental caries attending the oral diagnosis dental clinic of a tertiary health facility in Lagos, Nigeria. Collected samples from carious lesions were cultured on selective Mitis Salivarius agar incubated anaerobically and characterized. Pure wild-type Streptococcus sp. isolated were subjected to antimicrobial assay against three commonly used mouthwashes obtained within the study area. Results: The participants were forty consenting adults consisting of 27 males and 13 females. Sixty-six bacterial isolates were obtained and identified as Streptococcus sp (n = 49; 74.2%), Enterococcus (n = 14; 21.2%), and the unidentified (n=3; 4.6%). Of the 49 Streptococcus sp, 18 (36.7%) were S. mutans, 16 (32.7%) were S. salivarius and 15 (30.6%) were S. mitis. The antimicrobial assay revealed various zones that were concentrated and mouthwash type dependent. At full strength (100% commercial stock solution), mouthwash containing 0.2% chlorhexidine gave a more anti-streptococcal activity followed by mouthwash containing 0.03% Triclosan. Conclusion: Commercial mouthwash may have antibacterial activities against oral S. mutans, S. salivarius, and S. mitis. The formulation containing 0.2% chlorhexidine showed more inhibitory activity against the wild-type Streptococcus sp isolated. It is critical to advocate for the use of mouthwashes with potent active ingredients such as chlorhexidine to promote better oral health.