Medium influence at methylene blue photodynamic efficiency in Candida albicans inactivation

Abstract

Oral candidiasis is an opportunistic infection caused by Candida albicans. Considering the disadvantages of treatment with antifungal agents, in particular, the development of resistance, photodynamic therapy (PDT) has shown to be an interesting alternative. PDT is a treatment modality that is based on the use of a photosensitizing agent and light in the presence of oxygen. Methylene blue, due to the low cost, has been widely tested in clinical PDT. Unfortunately, due to a lack of standardization of clinical protocols, AM PDT often is reported in the literature that PDT does not bring additional benefits compared to other treatment modalities. In particular, due to the physicochemical peculiarities, methylene blue may have activity modulated due to its mechanism of action be defined by its physical state. In this sense, the identification of relationships between aggregation, mechanism of action, and effectiveness, as well as the establishment of media and formulations that may favor the most effective mechanism is essential. This study aims to evaluate the efficacy of photodynamic therapy with methylene blue varying the media of treatment in the control of C. albicans in vitro in order to establish relationships between the state of aggregation, effectiveness, and photochemical mechanism. Samples containing C. albicans will be irradiated with red LED in the presence of methylene blue in different vehicles and, after dilution will be grown in Petri dishes containing Sabouraud dextrose agar, and colony-forming units will be counted after 24h incubation at 37 °C. Through results obtained by this project, we expect to obtain relevant information to propose more efficient clinical trials for the treatment of oral candidiasis.