THE ROLE OF PENICILLIN-BINDING PROTEINS FOR BETA-LACTAM RESISTANCE INA BETA-LACTAMASE-PRODUCING BACTEROIDES UNIFORMIS STRAIN

The penicillin-binding proteins (PBPs) in two strains of Bacteroides u niformis were visualized and identified by gel electrophoresis and sub sequent fluorography. One of the strains (B. uniformis B 371) was high ly beta-lactam resistant and beta-lactamase producing, and the other w as a reference ATCC type strain (ATCC 8492). Clavulanic acid was used in the assay to block the beta-lactamase activity. Five major PBPs cou ld be demonstrated, ranging in molecular weights from 66-92 kD. The PB P patterns of the two strains were similar except for PBP 4, which had a slightly higher molecular weight in the resistant strain B. uniform is B 371. A competition assay with ampicillin, piperacillin, cephaloth in and cephaloridine showed differences in binding to the PBPs of the two strains. The binding of piperacillin to PBP 1 was more than ten-fo ld lower in the B 371 strain compared with the ATCC 8492 strain. The I C(50)s of piperacillin, cephalothin and cephaloridine for PBP 4 were b etween seven and 300-fold higher in the B 371 strain than in the ATCC strain. (C) 1996 Academic Press