ANTIBIOTICS IN BOVINE STAPHYLOCOCCAL MASTITIS - SENSITIVITY, RESISTANCE AND CLINICAL EFFECTS

Antibiotic sensitivity testing is less important in staphylococcal mastitis than bacterial isolation and identification. Resistance patterns are constant and well known: 60 to 75 % of S. aureus strains produce penicillinase; resistance to penicillinase-resistant penicillins and cephalosporins does not occur, and resistance to other antibiotics is rare. Therapeutic results depend more on various host- and herd-associated factors than on in vitro sensitivity. Cure of infections caused by coagulase-negative staphylococci is more readily achieved than with S. aureus infections. Acquired resistance tends to further decrease the low response rates typical of chronic S. aureus mastitis.