Study of the effectiveness of antimicrobial Photodynamic Therapy in the inactivation of Candida spp. biofilms

Abstract

Photodynamic Therapy (PDT) has been suggested as an alternative method to the inactivation of Candida species. In this context, the evaluation of effective photosensitizers for microbial inactivation is necessary for the viability of this clinical practice. The aim of this study is to evaluate the effectiveness of PDT mediated by hydrogel Photodithazine ® (PDZ-chlorine e6 derivative) in killing single species biofilms formed by standard strains (ATCC) of C. albicans, C.glabrata and C. tropicalis. Additionally, it will be evaluated biofilms formed by the associations of Candida albicans with Candida glabrata and Candida albicans with Candida tropicalis. Standardized suspensions of each strain will be performed, and after 48 hours of biofilms formation, they will be treated with 150 and 175 mg / L of PDZ for 20 minutes (pre-irradiation time), and exposed to LED light at 37.5 J/cm2 (660 nm) for 9 minutes. Cells suspensions will be treated only with additional PDZ or light, and control will consist of samples that will not receive PDZ nor light. Serial dilutions of the samples will be plated on Sabouraud Dextrose Agar and CHROMagar Candida. After 48 hours at 37 ° C, the viable colonies will be quantified. Additionally, crystal violet staining will be performed to determine the total biomass of the biofilms after PDT. All nine samples will be conducted in three separate occasions in duplicate for each experimental condition. The results will be analyzed by the most appropriate statistical method.(AU)