Antimicrobial susceptibility and beta-lactamase characterization of Branhamella catarrhalis isolates from 1983/1984 and 1988.

Branhamella catarrhalis isolates from lower respiratory tract specimens collected in 1983/84 (n = 50) and 1988 (n = 30) were examined for beta-lactamase production. The percent of beta-lactamase-producing strains increased from 25% to 63% from 1983/84 to 1988. beta-lactamases from 30 strains could be typed, and of these 28 were of the BRO-1 type and two the BRO-2 type. The two beta-lactamase inhibitors, clavulanic acid and brobactam were very active against beta-lactamase extracts whether of the BRO-1 or the BRO-2 type. Susceptibility to a number of antimicrobial agents or combinations of agents was determined by a plate dilution method (MICs) and by a tablet diffusion method. The penicillin tablet (Rosco Neo-Sensitabs) was found to be useful in discriminating between beta-lactamase-producing and non-beta-lactamase- producing strains of B. catarrhalis.