Isolation of major pathogens from cattle with subclinical mastitis and determination of antibiotic susceptibilities

Bacterial factors causing bovine mastitis are divided into two groups according to origin and transmission routes. The first major contagious agents are S. aureus, Streptococcus sp. and E. coli. These factors are spread widely, especially with handling and milking units. The aim of the study was to determine the isolation and antibiotic susceptibility of S. aureus, Streptococcus sp. and E. coli, which are very important for milk production and frequent agents of subclinical mastitis. In our study, 138 samples of dairy cows from Aydin province with subclinical mastitis problem were taken aseptically. In coclusion, 102 (18.5%) S. aureus, 21 (3.8%) Streptococcus sp., and 15 (2.7%) E. coli were isolated from the 552 milk samples examined. After PCR with specific primers in genotypic identification, all isolates were confirmed with regard to bacterial identification. S. aureus, Streptococcus sp. and E. coli isolates were susceptible to antibiotics of amoxicillin-clavulanic acid, oxytetracycline, cefoperazone and cephalexin-kanamycin.