Efeito antimicrobiano de dinoponeratoxinas sobre cepas de Staphylococcus aureus formadoras de biofilmes

Abstract

Staphylococcus aureus is a highly virulent pathogen, capable of biofilm formation and responsible for thousands of deaths each year. The prevalence of Methicillin-Resistant S. aureus (MRSA) strains has increased in recent years and thus, the development of new antibiotics has become necessary. Antimicrobial Peptides (AMPs) are effective against a variety of multidrug-resistant bacteria and low levels of resistance have been reported regarding these molecules. Dinoponera quadriceps ant venom (DqV) has been described regarding its effect against S. aureus. In this study, we have evaluated the antibacterial effect of DqV-AMPs, the Dinoponeratoxins (DNTxs; M-PONTXDq3a, -Dq3b, -Dq3c and -Dq4e), against Methicillin-Sensitive (MSSA) and a MethicillinResistant S. aureus (MRSA) strains. DNTxs were tested against MSSA ATCC 6538P and MRSA ATCC 33591, both biofilm formers. The minimum inhibitory concentration (MIC), minimum lethal concentration (MLC) and rate of kill were performed by microdilution on broth and subcultive on the surface of agar. Minimmal Inhibitory Biofilm Concentration (MIBC) and alteration in membrane permeability was measured by crystal violet technique. Morphology alterations were observed by scanning electron microscopy (SEM). MSSA ATCC 6538P showed better results on M-PONTXDq3a (MIC=0.78 µM; MLC=1.56 µM), so MIC, MLC, MIBC were determinated for both strains, showing results between 0.78 and 3.12 µM. Rate of kill, alterations in membrane permeability and SEM were performed on MSSA ATCC 6538P treated with M-PONTXDq3a, showing time of kill at 6 hours, membrane disruption on Crystal Violet technique and SEM. M-PONTX-Dq3a demonstrates to be a biologically active antimicrobial peptide against strains of MSSA and MRSA, as well as opens up new perspectives for the prevention of biofilm formation through the development of antiadhesive surface coatings on medical devices, as well as the treatment of resistant strains in skin or soft tissue infections.