Fotoinativação de Candida albicans utilizando azul de metileno como fotossensibilizador.

Abstract

Introduction: Candida albicans is a major challenge to public health because of to the amount of resistant species. Objective: To evaluate the effect of photodynamic therapy in the inactivation of Candida albicans planktonic cells (ATCC10231), using methylene blue, 150 mg / mL, as a photosensitizer. Method: Aliquots of 100 ug / ml of the fungal suspension in a 106 cells / ml concentration were seeded in microtiter plates with 96 wells, which was deposited with the same volume of methylene blue, remained at a 5 min pre-irradiation. Then, it was applied low power laser light (wavelength: 660 nm, power: 100 mW and dose: 426 J / cm2 ) for 128s using a portable semiconductor laser (Laser DUO®, GaAlAs, InGaAlP, MM OPTICS LTDA, São Carlos, SP Brazil). Control experiments were performed without illumination, in the absence and presence of methylene blue and with illumination replacing the photosensitizer by saline. In each experimental condition, serial dilutions (10-1 to 10-3) were obtained and 25 uL aliquots were seeded in Sabouraud Dextrose Agar duplicate . After this period, the number of colony forming units per milliliter (CFU / mL) was determined and the data were submitted to variance analysis and Kruskal Wallis test (p <0.05). Results: At the concentration of 150 ug / ml, and time of 5 min incubation, the reduction was significant (P0.05) in the absence of irradiation, methylene blue produced no reduction in CFU / mL. Conclusion: Photodynamic Therapy presented antifungal effect against Candida albicans and can be used as an adjunct to conventional treatment.