In vitro activity of azlocillin, carbenicillin, mezlocillin and piperacillin against Pseudomonas aeruginosa.
50% inhibitory concentration (IC50) of azlocillin, carbenicillin, mezlocillin and piperacillin against 157 strains of P. aeruginosa were determined by means of the agar plate-dilution method. The 3 new semisynthetic penicillins were significantly more active against P. aeruginosa than carbenicillin; azlocillin and piperacillin were 8-fold, and mezlocillin was 2-4-fold more active than carbenicillin. More than 95% of the P. aeruginosa strains were inhibited by 16 micrograms/ml of azlocillin or piperacillin whereas 64 micrograms/ml of mezlocillin and 256 micrograms/ml of carbenicillin, respectively, were necessary to inhibit 95% of the strains.
D001390:Azlocillin; D002228:Carbenicillin / Q000494:pharmacology; D008802:Mezlocillin; D008826:Microbial Sensitivity Tests; D010406:Penicillins / Q000494:pharmacology*; D010878:Piperacillin; D011550:Pseudomonas aeruginosa / Q000187:drug effects*
D010406:Penicillins; D002228:Carbenicillin; D001390:Azlocillin; D008802:Mezlocillin; D010878:Piperacillin