Use of photodynamic therapy and chitosan for inactivacion of Candida albicans in a murine model.

Background: The wide use of topical and systemic antifungal agents as the conventional treatment for oral candidiasis has caused Candida albicans to develop resistance to these agents. The aims of this study were to evaluate the effects of photodynamic therapy (PDT) and chitosan on buccal candidiasis and study the possible enhancive effect of chitosan on the photosensitizer methylene blue.

Methods: Thirty-five DBA/2 immunosuppressed mice were orally inoculated with a suspension of Candida albicans. The animals were randomized into seven groups (n = 5 per group): Group 1 (control); Group 2 (nystatin); Group 3 (PDT); Group 4 (chitosan 1.5 mg/ml); Group 5 (chitosan 3 mg/ml); Group 6 (PDT + chitosan 1.5 mg/ml); and Group 7 (PDT + chitosan 3 mg/ml). The Candida albicans count was evaluated on days 3, 5, 7, and 11 after inoculation. At last, macroscopic and microscopic analyses of the tongue dorsa were performed.

Results: On day 7 after inoculation, the control group showed a greater number of Candida albicans (5.25 ± 0.41 log10 CFU/ml), with significant differences compared to all other groups (P ≤ 0.05). On day 11 after inoculation, animals treated with PDT showed lower CFU/ml count. Groups 2, 3, 4, 5, and 6 showed fewer microscopic candidiasis lesions than Groups 1 and 7.

Conclusions: PDT has an antifungal effect, even greater than nystatin. Chitosan has a powerful fungicide effect but did not possess any enhancive effect on methylene blue.