ANTIMICROBIAL SUSCEPTIBILITY OF STRAINS OF Staphylococcus aureus AND Staphylococcus COAGULASE-NEGATIVE ISOLATED FROM COWS’ MILK WITH MASTITIS IN THE WEST OF PARANÁ, BRAZIL

Resumo

Mastitis, inflammation of the mammary gland, is one of the most common diseases of dairy cattle, and the important bacterial infectious agent is Staphylococcus sp., which commonly presents resistance to the antibiotics used in the treatment of mastitis. For this reason, this study was aimed at drawing the profile of anti-microbial sensibility of 60 strains of coagulase-negative Staphylococcus (CNS) and 45 strains of Staphylococcus aureus isolated from samples of dairy cattle with mastitis. The tests of anti-microbial sensibility were accomplished through a disk-diffusion technique for 14 antibiotics, it being verified that the most effective in vitro drugs was cefepime (97.9%) for CNS and for S. aureus the most effective was norfloxacin (89.1%). The least effective in vitro drug was penicillin, its susceptibility was 7.3% and 7.5% respectively for CNS and S. aureus. The strains that presented resistance for three different classes of antibiotic were considered multi-resistance. Among CNS, 28.5% were multi-resistant and 64.4% for S. aureus. The conclusion is that penicillin, which is widely used in veterinary medicine, is not a good option for treatment of bovine Staphylococcus mastitis, since this study showed a low in vitro susceptibility. The analysis of the anti-microbial susceptibility in vitro should be considered by the veterinarians and owners, especially before taking decisions about the choice of the appropriate treatment in order to reduce losses in milk production and improve the control programs.