IMIPENEM RESISTANCE OF PSEUPOMONAS AERUGINOSA

1. RELATIONSHIP OF RESISTANCE BET WEEN AND OTHER β LACTAM ANTIBIOTICS

Abstract

We determined the susceptibility of 70 clinical isolates of imipenem resistant Pseudomonas aeruginosa to ceftazidime (CAZ), cefsulodin (CFS), refotaxinie (CTX), latamoxef (LMOX), piperacillin (PIPC), and aztreonam (AZT). Twenty strains (29%) produced β-lactamase at low levels, and were susceptible to other antipseudomonal β lactams (CAL, CFS, PIPC, AZT). These strains were classified as group A. The production of β lactamases by the induction of antipseudomonal lactams, except imipenem, was low in the group A strains. Resistance of the group A strains to imipenem only was thought to be due to the low permeation of the drug. Fifty strains (71%) showed cross-resistance to other antipseudomonal β-lactams and these strains were classified as group B. The group B strains produced β-lactamases at high levels by the induction of these antibiotics or dereppresseclly. Resistance of the group B strains to imipenem and other antipseudomonal β-lactams was thought to be due to the low permeation of imipenem and the high production of the β-lactamases.