In vitro activity of cefuroxime against Moraxella (Branhamella) catarrhalis

Minimal inhibitory concentrations of cefuroxime were determined by an agar dilution procedure and compared with erythromycin and four other beta-lactam antibiotics (amoxycillin, amoxycillin + clavulanate, cefadroxil, cefaclor) on 76 strains of Moraxella (Branhamella) catarrhalis. Sixty four of them produced a beta-lactamase. Results show that the beta-lactamase of Moraxella (Branhamella) catarrhalis abrogates the activity of amoxycillin (MIC 90% = 4 mg/l) meanwhile the combination of amoxycillin-clavulanate is inhibitory at low concentration (MIC 90% = 0.25 mg/l). There are no difference in MICs between strains producing or not producing beta-lactamase with erythromycin (MIC 90% = 0.25 mg/l). All the strains evaluated in this investigation, producing or not producing beta-lactamase have MIC 90% less than or equal to 2 mg/l for cefuroxime lower than those obtained for the two other cephalosporins.