Comparison of imipenem and five other antipseudomonal agents against gentamicin-susceptible and -resistant Pseudomonas aeruginosa.

The in vitro activities of imipenem, aztreonam, piperacillin, ciprofloxacin and amikacin were tested by the microbroth dilution technique against 86 clinical isolates of Pseudomonas aeruginosa. Imipenem and ciprofloxacin were the most active agents against gentamicin-susceptible P. aeruginosa. Only imipenem inhibited gentamicin-resistant P. aeruginosa at < or = 8 micrograms/ml. The finding that none of the gentamicin-resistant strains were resistant to imipenem and amikacin indicated the superiority of these antibiotics to the other agents in hospital-associated gentamicin-resistant P. aeruginosa infections.