Anais do Congresso Paranaense de Microbiologia
IV Congress of Microbiology in Paraná

Not recently Staphylococcus aureus has been presenting itself as a bacterium of great epidemiological importance. Included in the World Health Organization's priority list, with a high degree of priority regarding the urgency for the development of new treatments, methicillin-resistant S. aureus (MRSA) is a global problem that needs to be addressed. However, few new drugs are in development, with many consisting of just reformulations or increasing doses of drugs already used. Thereby, Fluopsin C has been increasingly standing, despite its setbacks regarding its toxicity. Previous studies have pointed out that the encapsulation of Fluopsin C by liposomes was able to reduce toxicity in in vitro tests, as well as improve the solubility of this compound in aqueous media. The objective of this study was to evaluate the activity of free Fluopsin C and two liposomal formulations against the Brazilian Epidemic Clone MRSA S. aureus BEC 9393. Fluopsin C was obtained by cultivating Pseudomonas aeruginosa strain LV in nutrient broth with copper chloride, kept under constant aeration at a temperature of 28 °C. The cell-free supernatant was purified using several chromatographic methods to obtain Fluopsin C. The liposomal encapsulation was obtained via extrusion with the formulation of soy phosphatidylcholine, cholesterol and polyethylene glycol (DSPE-PEG) and another formulation without DSPE-PEG, with both performing passive encapsulation of Fluopsin C. These formulations were previously physicochemically characterized. The evaluation of antimicrobial activity was performed using the microdilution test in Mueller Hinton broth in accordance with CLSI standards, against S. aureus BEC 9393 to obtain the Minimum Inhibitory Concentration (MIC) and subsequent plating of the dilutions for results of Minimum Bactericidal Concentration (MBC). The results after 24 hours showed that the MIC for the two formulations and for free Fluopsin C were equal, of 0.41 µg/mL and this activity was maintained, and the MBC was also 0.41 µg/mL for all the conditions. Because of this, we can point out that Fluopsin C maintains its antibacterial activity against S. aureus MRSA after its encapsulation, adding advantages in terms of cytotoxicity, which will be evaluated in vivo in the future.