Efeito antifúngico do anlodipino em cepas de Candida spp. e em biofilmes mistos com Staphylococcus aureus resistente à meticilina (SARM): avaliação in vitro

Abstract

Antimicrobial resistance (AMR) has become one of the main threats to global public health, driven by the excessive and inappropriate use of antimicrobials , which favors the emergence and spread of multidrug-resistant strains. In this context, invasive fungal infections caused by Candida yeasts have become a growing problem, with candidemia associated with high mor-tality rates (30-40%). Simultaneously, Methicillin-Resistant Staphylococcus aureus (MRSA) remains an important bacterial pathogen, responsible for infections ranging from skin condi-tions to potentially fatal situations. The management of these infections is even more challen-ging due to the ability of these microorganisms to form biofilms, communities adhered to sur-faces, which offer significant protection and confer antimicrobial tolerance up to a thousand times greater than in planktonic cells. Medical devices, widely used in clinical procedures, re-present environments conducive to the formation of these biofilms, especially when there is colonization by Candida spp. and MRSA. The objective of this study was to investigate the antifungal activity of amlodipine against Candida spp. strains in planktonic and biofilm forms, to elucidate its possible mechanism of action, and to evaluate its effect on mixed biofilms of Candida spp. and MRSA, both in 96-well polystyrene plates and in Peripheral Venous Cathe-ters (PVCs). To this, an Antifungal Susceptibility Test was performed to determine the Mi-nimum Inhibitory Concentrations (MICs). The action of amlodipine against Candida spp. and Candida spp. plus MRSA biofilms was determined by the MTT assay, and its possible me-chanism of action was investigated through flow cytometry tests. The results demonstrated that amlodipine exhibited Minimum Inhibitory Concentrations (MICs) ranging from 62.5 to 250μg/mL, as well as significant action on mature and pre-formed and forming biofilms, promoting reductions between 50% and 90%. Additionally, the drug increased phosphatidyl-serine externalization and reduced fungal cell viability, suggesting induction of apoptosis. It was also observed that amlodipine reduced metabolic viability by approximately 90% in “in vitro’ polymicrobial biofilms at a concentration equivalent to 8xMIC (1000-2000 μg/mL), in all combinations tested, as well as exerting a potent action on mixed biofilms in CVPs, with a reduction in the number of colonies between 60% and 90%. Furthermore, the morphology was evaluated by light microscopy, confirmed by Scanning Electron Microscopy (SEM). Ba-sed on these findings, amlodipine emerges as a potential candidate for the treatment of fungal and mixed infections. However, additional in vivo studies are needed to validate and expand these results