In vitro study of photodynamic therapy with visible laser systems applied to fungal infections

Abstract

Evaluate the “in vitro” effect of the 660-nm laser on the inactivation of planktonic cells of Candida albicans, by the application of 660-nm diode laser light (1) on its own and (2) together with photodynamic therapy using methylene blue. We will also compare the ability of microbial inactivation of the laser over octenidine dihydrochloride disinfectant. This study was conducted in a laminar flow cabinet with 4 groups, divided into two: no laser groups—C. albicans suspension in saline solution (Group 1) and C. albicans suspension, with octenidine dihydrochloride antimicrobial solution (Group 2); laser groups—C. albicans suspension, using a 660-nm diode laser with photodynamic therapy and methylene blue (Group 3), and C. albicans suspension, using a 660-nm diode laser without the presence of methylene blue as photosensitizer (PS) (Group 4). They were seeded in 96 wells where we applied laser light in different light conditions in order to get reliable results. The results of this study demonstrate that the application of a 660-nm laser, with and without the presence of a photosensitizer, showed microbial inhibition ability against Candida albicans. Photodynamic therapy using the methylene blue photosensitizer presented an antifungal effect against Candida albicans of 100% efficacy, similar to the results obtained with octenidine dihydrochloride. The application of photodynamic therapy has demonstrated to be a good alternative, with an effective antifungal effect against Candida albicans, avoiding the side effects on patients, like those from octenidine dihydrochloride.