Resistance patterns of ovine mastitis pathogens

For control of the udder health status of milk sheep the minimal inhibitory concentration of mastitis causing pathogens to 12 different chemotherapeut ics was determined by means of Sensititre(R)-microplate method. 73 staphylo cocci- and 8 streptococci-strains was examined. Following staphylococci-str ains were found: S. aureus (11), S. epidermidis (34), S, chromogenes and S. xylosus (6 each), S. hyicus and S. warneri (each 5) as well as S. sciuri a nd S. simulans (3 each). MIC-values to penicilline, amoxycillin and ampicil lin of 2 penicillinase-positive S, aureus-strains were more than 4.0 mu g/m l. The remaining isolates and the major part of coagulase-negative staphylo cocci displayed MIG-values up to 1.0 mu g/ml to beta-lactamantibiotics exce pt cloxacillin. Against cephalosporines, cephalexin excluded, and aminoglyc osides very low MIG-values concerning staphylococci were observed. In case of spiramycin MIG-levels more or less than 8.0 mu g/ml were determined. Str eptococci exhibited MIG-values in the range of 0.06 to 0.5 mu g/ml against beta-lactamantibiotics with exclusion of cloxacillin, cefoperazone and cefq uinome and spiramycin as well.