Inativação fotodinâmica dos fungos causadores de onicomicoses Trichophyton rubrum e Microsporum gypseum

Abstract

Onychomycosis is one of the most common diseases in the field of dermatology and refers to a fungal infection of the nail plate with a high incidence in the general population. The available treatment options for onychomycosis have limited use due to side effects, drug interactions, and contraindications, which requires the application of an alternative treatment for onychomycosis. In the last years, the antimicrobial Photodynamic Therapy (aPDT) has been acknowledged as treatment options for several infectious diseases, including dermatological ones. However, the ideal parameters for a safe and effective therapy in the treatment of onychomycosis are still not fully elucidated. Therefore, this study aimed to evaluate the effectiveness of aPDT, in vitro, on the fungi Trichophyton rubrum (T. rubrum) and Microsporum gypseum (M. gypseum), the main causes of onychomycosis. In the in vitro tests, the fungi T. rubrum (ATCC 28188) and M. gypseum (ATCC 24102) were used, divided into 13 experimental groups: Group C (control - no treatment); group MB (treated with methylene blue); group R100 (treated with LED at a dose of 100 J/cm2) and groups T10, T20, T30, T40, T50, T60, T70, T80, T90 and T100, treated with luz at doses of 10 J/cm2 , 20 J/ cm2 , 30 J/cm2 , 40 J/cm2 , 50 J/cm2 , 60 J/cm2 , 70 J/cm2 , 80 J/cm2 , 90 J/cm2 , and 100 J/cm2 . For the treatment, a light-emitting diode (LED) equipment with a wavelength of 630 nm (100 mW; 2.93 cm2 ) associated with a photosensitizer was used, AM was used at a concentration of 100 μM, using 30’ of pre-irradiation. It was observed that aPDT reduced germination on T. rubrum germination with an energy density from 20 J/cm2, reaching achieving its eradication with an energy density of 100 J/cm2. In relation to M. gypseum, the influence on germination was proportional to the energy density, in the energy density of 100 J/cm². These results suggest that aPDT may be a possible and attractive alternative treatment for combating onychomycosis, although further investigation is needed to determine whether such efficacy could be achieved in vivo.