Factors associated with cure after therapy of clinical mastitis caused by Staphylococcus aureus

One hundred and fifty-nine cases of clinical Staphylococcus aureus mastitis were analyzed to detect factors associated with bacteriological cure after therapy. On 100 Dutch dairy farms, data were collected from four clinical trials with five intramammary treatment regimes designed to treat beta-lact amase-positive pathogens. Infected quarters were treated three times, with a 12-h interval between treatments. Treatment was extended for 2 d if resul ts of the trial treatment were, according to the owner, not satisfactory. T he overall bacteriological cure rate was 52%. The bacteriological cure rate of clinical beta-lactamase-negative S. aureus mastitis was significantly h igher than that of clinical P-lactamase-positive S. aureus mastitis. Bacter iological cure was also significantly higher if somatic cell count of the c ow was low at the milk recording prior to the onset of the clinical mastiti s. The bacteriological cure rate of clinical beta-lactamase-negative S. aur eus mastitis was also significantly higher after an extended treatment comp ared with no extended treatment. The seriousness of the various clinical sy mptoms and the bacteriological cure rate of clinical S. aureus mastitis wer e not associated.