Atividade in vitro da nisina sobre Staphylococcus aureus isolados de mastite bovina

Abstract

Staphylococcus aureus is the most isolated bacterial agent from cases of bovine mastitis. Its resistance to antimicrobials previously reported and has been growing in recent decades, the reality that extends to most pathogens in veterinary and human medicine. Nisin is part of a group of alternative natural antibiotics, called bacteriocins, widely exploited in food preservation and which has potential in clinical use against variations. Thus, the objective was to evaluate the in vitro activity of free nisin on 25 strains of Staphylococcus aureus isolated from bovine mastitis. The sensitivity was evaluated through the Minimum Inhibitory Concentration (MIC) using microdilution in 96-well plates with confirmed by resazurin developer, and by Minimum Bactericidal Concentration (MBC) through bacterial growth on Mueller-Hinton Agar. The MIC values found for S. aureus were 250 IU / ml the maximum and 156, 25 IU / ml the minimum and for CBM values of 625 IU / ml the maximum and 250 IU / ml the minimum. The results allow us to conclude that pure nisin showed considerable activity on strains of S. aureus and that formulations containing nisin represent an alternative for the treatment of mastitis caused by this agent. Based on the literature, further studies are in order to develop formulations that ensure solubility, stability and activity under physiological conditions.