Susceptibility of Pseudomonas aeruginosa to cefoperazone, cefotaxime and moxalactam, with special reference to isolates resistant to aminoglycosides, carbenicillin and ticarcillin

Cefoperazone, cefotaxime, and moxalactam were tested for inhibitory activity against 169 Pseudomonas aeruginosa clinical isolates previously characterized for their susceptibility to gentamicin, tobramycin, amikacin, carbenicillin, and ticarcillin. Cefoperazone was found the most effective of the compounds with 90% inhibition at 25 mg/l, and 50% inhibition at 6.25 mg/l. The relative effectiveness of cefoperazone, cefotaxime, and moxalactam was found to be 4 : 1 : 2, respectively. Isolates resistant to one or more of the aminoglycosides, carbenicillin, and ticarcillin, demonstrated significantly increased resistance to cefoperazone, cefotaxime, and moxalactam.