Comparative in vitro antibacterial and antifungal efficacy of chemical, herbal and probiotic mouthrinses against Streptococcus mutans and Candida species

Abstract

Background: Dental caries and oral candidiasis are predominant biofilm-associated infections, primarily driven by Streptococcus mutans and Candida species. While mechanical plaque removal is fundamental, mouthrinses are widely used as adjunctive treatments. This study evaluated and compared the in vitro antibacterial and antifungal efficacy of commercially available chemical, herbal and probiotic mouthrinses against key oral pathogens. Methods: 15 commercial mouthrinses, comprising five each of chemical, herbal and probiotic formulations were tested against S. mutans MTCC 457, Candida albicans MTCC 227 and clinical isolates of C. albicans, C. tropicalis and Pichia kudriavzevii. Antibacterial and antifungal activity was assessed using the agar well diffusion method. Zones of inhibition were measured following 24 - 48 hours of incubation at 37°C with positive controls penicillin or fluconazole. Results: Chemical mouthrinses demonstrated the strongest antimicrobial activity, where Hexidine produced the largest mean ZOI, followed by Colgate maXFresh PLAX. Herbal formulations such as Himalaya active fresh and K. P. Namboodiri’s Herbal Fresh showed moderate efficacy. Probiotic mouthrinses displayed limited and selective activity, primarily against S. mutans and non-albicans Candida spp., with Perfora probiotic rinse demonstrating the highest mean ZOI. Several products in each category produced no measurable ZOI. Conclusions: Chlorhexidine based mouthrinses remain the gold standard for rapid, broad-spectrum microbial reduction. Herbal formulations provide a moderate, phytochemical dependent alternative with a safer profile, while probiotic mouthrinses offer limited but selective antimicrobial effects