Abstract

Minimum inhibitory concentrations were determined for penicillin G, ampicillin, cloxacillin, neomycin and enrofloxacin against 39 Staphylococcus aureus strains isolated from bovine subclinical mastitis in three locations of the IX Region of Araucanía (Chile), in order to evaluate their in vitro susceptibility patterns. Agar diffusion and dilution tests were used according to NCCLS recommendations. Strains producing betalactamase were also determined by a chromogenic cephalosporin method. High resistance levels to penicillin G and ampicillin was detected. Cloxacillin, neomycin and enrofloxacin demonstrated activity against all strains. Results obtained here emphasize the necessity of establishing resistance plan monitoring for treatments applied in Veterinary Medicine. This concept, acquires greater importance considering the role of the veterinarian in public health protection.