Effect of Multiple Sessions Antifungal Photodynamic Therapy Using Erythrosine Combined with Potassium Iodide on Candida albicans Biofilm

Multiple-session photodynamic therapy (PDT) with two photosensitizers enhances the PDT efficacy. Candida albicans biofilms (ATCC10231) were treated with 200/100 µM erythrosine, 100 mM KI, or a combination. Control groups were phosphate buffer saline, 1:100, 000 U/ml nystatin, and light-only respectively. Experimental groups were exposed to LED (520 nm peak, 250 mW/cm², 10 J/cm²/session) for 1, 2, or 3 sessions in dark environment, with a 5 mins pre-irradiation and interval time in a triplicate fashion. Biofilm counts were log-transformed and compared at 0, 1, 6 and 24 hrs using median ± interquartile range. Statistical significance was determined with the Kruskal-Wallis with post hoc test at p < 0.05. 100 or 200 µM erythrosine + 100 mM KI with 2 and 3 sessions exhibits an antifungal effect comparable to nystatin. 100 µM erythrosine + 100 mM KI with 2 sessions green LED (20 J/cm²) effectively inhibited C. albicans biofilm.