Mastites clínicas e subclínicas em bovinos leiteiros ocasionadas por Staphylococcus coagulase-negativa

Abstract

This study aimed at assessing the feasibility of coagulase-negative Staphylococcus (SCN) as the etiologic agent of clinical and subclinical mastitis in dairy cattle in the southern region of Minas Gerais state, and to identify the bacteria species involved and to trace their profiles of susceptibility to antimicrobial drugs. The study included 2,492 cows from 35 herds, under different management systems, in the period of 2004-2008. The rates of clinical and subclinical mastitis were of 9.87% and 52.2%, respectively. The aseptically collected milk samples (1,645) from infected udders were cultivated, and 120 strains of SCN were isolated. The average frequency of isolation was found in 8.35% among the herds, varying from 0% to 27.27%. A high diversity of SCN species was isolated, an the most frequent were Staphylococcus hyicus (15.0%), Staphylococcus chromogenes (12.5%), Staphylococcus gallinarum (12.5%), Staphylococcus lentus (12.5%) and Staphylococcus epidermidis (10.8%). The antimicrobial susceptibility testing showed that 28% of the strains were resistant to penicillin, 21% to streptomycin, 18% to ampicillin and 14% to tetracycline. All strains showed 100% susceptibility to danofloxacin, enrofloxacin and florfenicol. Low frequency of multiresistant strains was found in the studied population.