Abstract
Milk is extremelly valuable to the human diet and an excellent substrate for the growth of a wide range of microorganisms, including Staphylococcus aureus, frequently found in raw milk and one of the most prevalent microorganisms in cases of bovine mastitis in the world. The objective of this study was to evaluate the sensitivity of S. aureus strains isolated from raw milk to commercial antimicrobials. For this end, antibiotics based on research were selected from commercial establishments of veterinary drugs in the municipality of Zé Doca (Maranhão State, Brazil). The antibiotics were identified by association with penicillin, streptomycin, isoniazid and prednisolone (PCB), oxytetracycline base (TOR), a combination of penicillin and streptomycin (MPP), and tetracycline hydrochloride (TCA). Subsequently, Staphylococcus spp. counting was perfomed, with isolation and biochemical identification of strains of S. aureus, which were then submitted to antibiograms with identification of beta-lactamase producing strains. The results showed contamination in all samples by Staphylococcus spp., with counts ranging from 1.9 x 103 to 5.24 x 106 CFU/mL. Among the antibiotics tested, TOR showed the highest efficiency in elimination or reduction of all S. aureus strains. We found that 50% of S. aureus strains isolated produced the enzyme beta-lactamase. It is necessary to create measures to combat the emergence of new bacterial strains and to promote action by public authorities, supervising the commercialization of veterinary drugs.
Keywords:
bacterial resistance; beta-lactamase; dairy products; milk quality