Estudo de eficácia antimicrobiana da terapia fotodinâmica em meio de cultura de Candida Albicans

Abstract

Introduction: Candida albicans is a fungus present in the flora of healthy individuals. However, such organisms in some pathologies can cause infections. The Photodynamic Therapy (PDT) uses a light source and a photosensitizing agent (PS) that when stimulated produces cytotoxic Reactive Oxygen Species (ROS), leading to apoptosis. The PDT presents antimicrobial action, including among multidrug-resistant microorganisms. Objective: To define the minimum inhibitory concentration (MIC) of methylene blue and orthotoluidine blue photosensitizers irradiated by a light-emitting diode (LED) in an in vitro culture of Candida albicans. Methodology: An in vitro analysis of different durations of exposure to the light source and serial concentrations of photosensitizers (PS), methylene blue and toluidine blue, was performed in order to demonstrate the inactivation of the fungus C. Albicans. The LED used has a wavelength of 630 nm, cluster power of 0.15w. The experiment was subdivided into three phases related to the dosages of PDT: 1st phase applied the LED for 30 seconds (11.84 J/cm2); 2nd phase the application time was reduced to 15 seconds (5.92 J/cm2); 3rd phase adopted the same dosage of LED but increasing the number of subgroups in order to confirm the effectiveness of PDT. Results: Methylene blue PS showed no favorable effects during the first phase, while toluidine blue underwent all three phases. The MIC of toluidine blue was not found in the first phase, however the last two phases 0.7μM showed promising results. Conclusion: This study demonstrated the antimicrobial efficacy of photodynamic therapy using toluidine blue in candida cultures. The feasibility of PDT may guide future studies involving Candida Albicans infections, being an effective treatment without adverse effects.