Evaluation of the Antifungal Effect of Lacticaseibacillus rhamnosus GG against Oral candidiasis in Healthy Sprague-Dawley Rats

Background Conventional treatments for oral candidiasis face limitations due to rising antifungal resistance and long-term toxicity. Probiotics, particularly, have shown antifungal potential, but their effects on non-albicans species like Candida tropicalis are not well understood. This study evaluated the therapeutic efficacy of Lacticaseibacillus rhamnosus GG against C andida albicans and C andida tropicalis in a rat model. Methods Sprague-Dawley rats were immunosuppressed using dexamethasone (0.5 mg/L) and tetracycline (0.1% initially, then 0.01%) in drinking water. A fungal suspension (1 × 10 7 CFU/mL) was applied topically to the tongue for three days, and probiotic (0.3 mL of 1 × 10 8 CFU/mL) was administered orally for 28 days. Microbiological analysis of tongue swabs was performed using culture and Gram staining on a weekly basis. At the end of the study, blood samples were analyzed for haematological and biochemical parameters, and tongue tissues were examined via histopathology, immunohistochemistry (TLR2, TLR4 and Msp1/p75), and Western blot. Statistical analyses were performed with GraphPad Instat 3.0. Results L. rhamnosus GG significantly reduced C. albicans and C. tropicalis colonization in immunosuppressed rats, with greater effects against C. albicans . Probiotic administration maintained normal haematological and biochemical parameters, reduced tissue invasion, and modulated immune responses, as evidenced by changes in TLR2, TLR4, and Msp1/p75 expression. These findings support the antifungal and immunomodulatory potential of L . rhamnosus GG as a complementary therapy for oral candidiasis. Conclusion The present study suggests that L . rhamnosus GG may contribute to the development of probiotic-based therapies as a potential adjuvant to antifungal therapy in oral candidiasis.