ETIOLOGY OF BOVINE SUBCLINICAL MASTITIS, SUSCEPTIBILITY OF THE AGENTS TO ANTIMICROBIAL DRUGS AND DETECTION OF THE GENE β-LACTAMASIS IN Staphylococcus aureus

Abstract

With the objective to study the etiology of subclinical mastitis and the susceptibility of the agents to antimicrobial drugs, 174 dairy cows of nine farms in Jataí-GO, where the animals were milked by hand were submitted to the California Mastitis Test (C.M.T.). Of these 96 (55,2%) were positive, with 163 (23,4%) positive quarters. In the sequence, milk of the infected quarters were collected, identifying 208 bacterial strains: 85 (40,9%) of Staphylococcus spp., 74 (35,6%) of Corynebacterium spp., 41 (19,7%) of Streptococcus spp. and eight (3,8%) of Escherichia coli., Staphylococcus was the most frequent isolated agent; in 31 samples (14,9%) it was possible to identify S. aureus, in 29 (13,9%) S. saprophyticus, in 17 (8,2%) S. xylosus, in four (1,9%) S. epidermidis and in two (1,0%) S. intermedius. The strains of S. aureus isolated of the milk  showed 100% of resistance to oxaciclin,  penicillin and ampicilin; the gene of beta-lactamase was found in 90,3% of the strains by the polymerase chain reaction technique, with a phenotypic resistance identity. The presented data suggest the relationship among the indiscriminate use of antimicrobial drugs  with the high index of resistance of the agents to the these drugs.