Antibiotic-sensitivity of bacteria isolated from cases of bovine mastitis

Antibiotic-sensitivity of 1748 strains of staphylococci, 632 strains of str eptococci and 301 strains of coliform bacteria Isolated from subclinical an d clinical mastitis in cows was examined. They were tested against penicill in, streptomycin, neomycin, terramycin, chloromycethin, erythromycin, ampyc illin and cloxacillin. The ent was performed by the paper disc method. Duri ng the ten-gear period of testing (1990-1999) a visible increase in resista nce of the bacteria was found in relation to terramycin (streptococci) and cloxacyllin (staphylococci). Neomycin and chloromycethin were the most effe ctive antibiotics against all three groups of bacteria in vitro. A high rat e of resistance against cloxacyllin was noted. On average from 69.1% (strep tococci) to 100% (coliform bacteria) of the strains were resistant to this antibiotic. A fluctuation of antibiotic-sensitivity within the same species of bacteria from one year to the next was noted. It was concluded that bac teria isolated from bovine mastitis did not show a significant increase in resistance to the majority of antibiotics.