Atividade antimicrobiana e antibiofilme de porfirinas catiônicas meso-tetra (piridil) contendo cisplatina

Abstract

Biofilms are responsible for up to 80% of antimicrobial-resistant nosocomial infections. Most of these infections are associated with the use of medical devices such as urinary catheters, and in this context, it is estimated that 90-100% of patients who undergo long-term catheterization develop bacteriuria, with Proteus mirabilis being the most prevalent microorganism, indicated as responsible for 20-45% of these infections. In view of the above, due to the difficulty of treating biofilms, new alternatives have been tested daily to fight infections and antimicrobial photodynamic therapy is an emerging strategy for the treatment of antimicrobial-resistant microorganisms. This therapy uses a photosensitizer and specific wavelength light to generate reactive oxygen species. Among the photosensitizers used, porphyrins have been extensively evaluated, since they have already been shown to be efficient against several microorganisms, in addition to the possibility that some are soluble in water. Thus, this work aims to evaluate the antimicrobial and antibiofilm activity of porphyrins on the ATCC 25933 strain of P. mirabilis and clinical isolates, as well as their cytotoxic and genotoxic effects on human mononuclear cells. The porphyrins 3-H2TPyP, 4-H2TPyP, 3-cis-PtTPyP e 4-cis-PtTPyP were evaluated in broth microdilution tests to determine the minimum inhibitory concentration and minimum bactericidal concentration. Time-kill assay, checkerboard assay, test with reactive oxygen species scavengers and conventional biofilm formation assay and biofilm with catheters were also performed. Tests were performed with human mononuclear cells in order to determine the cytotoxicity and genotoxicity of porphyrins. The results of the microdilution tests showed greater efficacy against P. mirabilis when the porphyrins were exposed to white LED light (370 to 800 nm), which also occurred when the time-kill test was performed at times 0, 2, 6 and 12h. P. mirabilis was considered a strong biofilm former when MH broth supplemented with 1% glucose was used. In biofilm assays (conventional and catheter), porphyrins obtained better results when irradiated with light. In the checkerboard assay, both porphyrins showed indifference when administered together. From the cytotoxicity and genotoxicity tests performed on human mononuclear cells, it was possible to observe that the porphyrin 3-cis-PtTPyP in the presence of light was the only one to show a decrease in cell viability in the MTT test. This same porphyrin caused DNA damage when not irradiated with light. None of the porphyrins caused an increase in DCF and nitrite in the tests performed. It can be concluded from the above that aPDT together with the use of porphyrins with cisplatin obtained positive results, and may become an alternative in the treatment of P. mirabilis infections.