Análise do efeito da terapia fotodinâmica antimicrobiana transtorácica na endocardite infecciosa por Staphylococcus aureus em modelo animal

Abstract

Infectious Endocarditis (IE), a severe infection of the cardiac endothelium with valvular vegetations, has an annual incidence of 3-10 cases/100,000 people and a 30-day mortality rate of 30%. Staphylococcus aureus is the main etiological agent. Given the prolonged treatment, bacterial resistance, and high costs, the search for innovative therapies is necessary. This study aimed to analyze the effect of antimicrobial Photodynamic Therapy (aPDT) on the survival of 72 male Wistar rats. IE was induced by inoculating S. aureus via a catheter introduced into the carotid artery to the heart valves. Animals were randomly allocated into three groups: control (IE), one session of aPDT (PDT1), and three sessions of aPDT (PDT3). The aPDT used methylene blue (10mg/kg), in 0.9% saline solution, and LED 660(±20) nm (360 J, 600 seconds, 129 J/cm²), with transthoracic sessions starting on the 4th day. On the 20th day, surviving animals were euthanized for histological and microbiological examinations of the valves. Results showed survival rates of 33.33% (IE), 50% (PDT1), and 91.66% (PDT3), with p<0.05. Bacterial colonies underwent significant reduction. Histological analyses of the treated groups revealed tissue reorganization and decreased inflammatory infiltrate, with more advanced repair in the PDT3 group. This study suggests that aPDT with methylene blue and LED 660(±20) nm is a promising therapeutic strategy for the treatment of Infectious Endocarditis