BETA-LACTAMASES OF MORAXELLA-CATARRHALIS

The enzymes called BRO-1 (formerly called "Ravasio-type") and BRO-2 (formerly called "1908-type") are the most predominantly observed beta-lactamases in clinical Moraxella catarrhalis isolates. Both of these enzymes can be observed on a worldwide scale, whereas other enzymes occur infrequently. The first beta-lactamase producing (bla+) isolate was detected in clinical specimens in 1976; at present however, 70 to 90 % of all clinical isolates are bla+. These enzymes are most likely transposon-mediated and can be observed in other members of the Moraxella family. The molecular weight ot the BRO-1 enzyme amounts to 33 kdal; it hydrolyses the penicillin derivatives very rapidly, to a lesser extent the older cephalosporins; however, the latter ones exhibit low affinity to the enzyme.