Evaluation of antifungal and antibiofilm effects of supernatant cell-free supernatant (CFS) of Lactobacillus casei alone and in combination with nystatin against Candida albicans strains

Abstract

Background and Objectives: Candida albicans (C. albicans) is the most common cause of candidiasis in immunocompro- mised patients. Biofilm-associated Candida can lead to treatment complications and systemic infections.

Materials and Methods: In this study, the antifungal activity of the cell-free supernatant (CFS) derived from Lactobacillus casei was assessed against C. albicans strains. To differentiate between pH- and H₂O₂-mediated effects and specific metabo- lite activity, all antifungal and antibiofilm assays were performed using CFS that had been neutralized to pH 7.0 and treated with catalase.

Results: The ranges of minimum inhibitory concentration (MIC) and Half-maximal inhibitory concentration (IC50) for CFS were 7.81-62.5 and 95.1-159.6 µl/ml, respectively. Using corrected FICI criteria (synergy ≤ 0.5; additive > 0.5-1.0; indiffer- ence > 1.0-4.0), additive effects were observed in 50% of strains, synergy in 20% (including the standard strain PTCC 5027), and indifference in 30%.

Conclusion: The results demonstrate that the CFS of L. casei exhibits promising in vitro antifungal and antibiofilm activity against C. albicans. When used in combination with nystatin, L. casei CFS showed additive or synergistic effects, suggesting its potential as an adjunctive agent for further investigation. However, these findings are preliminary, and in vivo studies and clinical assessments are necessary to validate the therapeutic potential of L. casei CFS in the management of oral candidiasis.