Abstract
The development of intricate dental biofilms and an imbalance in the oral microbiota are linked to Early Childhood Caries (ECC) as a multifactorial oral disease. Although Streptococcus mutans has been extensively studied, other microorganisms, including Streptococcus sobrinus and Candida albicans, also contribute significantly to the severity of ECC. Probiotics like Limosilactobacillus reuteri, which produce antimicrobial metabolites, such as reuterin, have shown potential as biofilm-modulating agents, but their effects on dual-species biofilms from ECC clinical isolates remain poorly understood. The inhibitory potential of L. reuteri against dual-species biofilms formed by clinical isolates of S. sobrinus with C. albicans obtained from children with ECC was evaluated by this study. Supragingival plaque sampling in ECC patients aged 3–5 years enabled the recovery of clinical isolates representing S. sobrinus as well as C. albicans. Dual-species biofilm cultures were grown in saliva-treated 96-well microplates. After incubation with L. reuteri (2 × 10⁸ CFU/mL), the accumulated biofilm was evaluated through crystal violet staining and absorbance measurement at 600 nm. The microbial count (CFU/mL) was determined by absolute real-time PCR, and the expression of virulence genes (gtfI and HWP1) was evaluated by utilizing relative real-time PCR. The reduction in biofilm biomass produced by treatment with L. reuteri was 35% (p < 0.05). In addition, there was a significant reduction in the microbial load of S. sobrinus and C. albicans. Expression of the virulence genes gtfI and HWP1 was notably downregulated following probiotic treatment (p < 0.05). L. reuteri exhibits potent antibiofilm and antivirulence effects against dual-species biofilms formed by ECC-associated clinical isolates. These findings support its potential as a biofilm-modulating agent for caries prevention strategies.