Avaliação da eficácia da terapia fotodinâmica com fotossensibilizante natural na inibição de bactérias de importância médica

Abstract

This study aims to describe Photodynamic Therapy (PDT) tests that were performed with different species of medically important bacteria, which are responsible for many nosocomial infections. In this technique, the use of a photosensitizer (PS) is employed to interact with the cells of interest and cause a photodynamic reaction, which uses the oxygen available in the environment to lead the cell to apoptosis. PDT is currently studied as an antimicrobial treatment, to aid in wound healing and also to treat tumors. The objectives of the study were to evaluate the effectiveness of PDT in inhibiting microorganisms of medical importance, verifying whether the time of submission to photodynamic treatment at different wavelengths, 254 nm and 365 nm, affects the growth of bacteria, and whether it demonstrates an effect inhibitory and bactericidal, using natural extract of Acmella oleracea (jambu) and Bixa orellana (urucum) as PS. For the experiment, solutions were prepared with the microorganisms from the 0.5 scale of McFarland (1:1; 1:10; 1:100 and 1:1000) and the photosensitizers diluted in different concentrations (0.1; 0.055 and 0.01 mg/mL), a Control Plate (PC) was prepared for each species and the microplates were submitted to ultraviolet light (UV) at 254 nm and 365 nm in a dark cabin, with a distance of 15 cm between the sample and the light source, for predetermined time intervals of 30 minutes and 60 minutes. Microplates were analyzed on the plate reader at 630 nm before submission to UV light and again after 24 hours for cell counting and data analysis. Resazurin was also used as a developer of microbial activity. The results showed an inhibitory effect on the growth of bacteria, which was not observed in all samples studied when compared to CP. In addition, light also caused an inhibitory effect in samples without PS application. The bactericidal effect was not observed. The species in which the most satisfactory results occurred was P. mirabilis, which proved to be more sensitive to the given conditions. Keywords: Pathogens; antimicrobial; Microorganism.