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.