Photodynamic inactivation of clinical isolates of Candida using Photodithazine®

This study evaluated the photodynamic inactivation (PDI) mediated by Photodithazine((R)) (PDZ) against 15 clinical isolates of Candida albicans, Candida glabrata and Candida tropicalis. Each isolate, in planktonic and biofilm form, was exposed to PDI by assessing a range of PDZ concentrations and light emitting diode fluences. Cell survival of the planktonic suspensions was determined by colony forming units (CFU ml(-1)). The antifungal effects of PDI against biofilms were evaluated by CFUml(-1) and metabolic assay. Data were analyzed by non-parametric tests (=0.05). Regardless of the species, PDI promoted a significant viability reduction of planktonic yeasts. The highest reduction in cell viability of the biofilms was equivalent to 0.9 log(10) (CFU ml(-1)) for C. albicans, while 1.4 and 1.5 log(10) reductions were obtained for C. tropicalis and C. glabrata, respectively. PDI reduced the metabolic activity of biofilms by 62.1, 76.0, and 76.9% for C. albicans, C. tropicalis, and C. glabrata, respectively. PDZ-mediated PDI promoted significant reduction in the viability of Candida isolates.