In vitro effect of over-the-counter probiotics on the ability of Candida albicans to form biofilm on denture strips

Abstract

Purpose: There is a burgeoning recognition and interest in the potential of probiotics in the treatment and prevention of oral candidiasis associated with the use of dentures. Our aim was to investigate if commercially available over-the-counter probiotics can influence the ability of Candida albicans to form biofilms, which is considered a hallmark of the initiation and progression of oral candidiasis.

Methods: We conducted a 2×5 factorial in vitro study to culture C. albicans on denture strips and challenge with one of the following four commercially available probiotics in bacterial or cell-free supernatant form: Accuflora®, Align®, Culturelle® and Sustenex®. C. albicans biofilm formation was studied in triplicates in all factorial combinations of the study and assessed qualitatively with fluorescence microscopy and quantitatively with tetrazolium salt (XTT) reduction assay. Quality control measures included determination of coefficient of variation, Bland Altman plots and Pittman's test. Results were analyzed using two-way analysis of variance (ANOVA) with pairwise post-hoc Scheffe's tests.

Results: Our experimental conditions passed the quality control checks. Two-way ANOVA results indicated that cell-free supernatants provided a stronger and significant inhibitory effect on biofilm formation than their bacterial counterparts (2-way ANOVA p=3.8×10(-6)). Further, Lactobacillus-containing probiotic formulations (Accuflora® and Culturelle®) significantly reduced biofilm formation especially in supernatant form.

Conclusion: Commercially available probiotics that contain Lactobacilli species interfere with the in vitro ability of C. albicans to form biofilms on dentures. The mechanistic and clinical implications of our results need to be addressed by larger in vivo studies.

Keywords: biofilm; candidiasis; dentures; experimental studies; probiotics.