In vitro susceptibilities and beta-lactamase production of 53 clinical isolates of Branhamella catarrhalis.

We tested 53 clinical isolates of Branhamella catarrhalis recovered from patients with respiratory symptoms to determine the susceptibility of the isolates to 25 antimicrobial agents, including the newer beta-lactam antibiotics. Of the 53 strains, 46 (86.7%) were beta-lactamase producers. All the strains were susceptible to the majority of the new penicillins and cephalosporins. The combinations of amoxacillin-clavulanic acid and ticarcillin-clavulanic acid were also very active against the beta-lactamase-producing strains.