SUPERIOR EFFECT OF TAZOBACTAM PIPERACILLIN COMPARED TO PIPERACILLIN ON BETA-LACTAMASE-PRODUCING PSEUDOMONAS-AERUGINOSA/

To evaluate the synergistic antimicrobial effects of tazobactam (TAZ), a p-lactamase inhibitor, and piperacillin (PIPC) on Pseudomonas aerug inosa, we compared the antimicrobial effects of TAZ/PIPC with those of PIPC alone on bacteria inducibly or constitutively producing beta-lac tamase. TAZ/PIPC had more potent antimicrobial effects compared with P IPC on clinical isolates producing beta-lactamase. In the treatment of mouse systemic infection, the therapeutic effect of PIPC was markedly decreased by beta-lactamase, but that of TAZ/PIPC was only slightly d ecreased. In the treatment of local infections in mice, the therapeuti c effects of PIPC were decreased due to the induction of beta-lactamas e and the emergence of bacterial strains constitutively producing beta -lactamase, while those of TAZ/PIPC were not affected.