Activity of Azlocillin and Mezlocillin Against Gram-Negative Organisms: Comparison with Other Penicillins

Abstract

The activities of azlocillin and mezlocillin were compared with those of carbenicillin, ticarcillin, and pirbenicillin against a wide range of gram-negative organisms. The two new drugs were considerably more active than carbenicillin against Klebsiella species and Escherichia coli . Carbenicillin was twice as active against Proteus mirabilis as mezlocillin and four times as active as azlocillin. Against Pseudomonas aeruginosa , azlocillin was eight times as active as carbenicillin. Azlocillin and mezlocillin were twice as active as carbenicillin against Bacteroides fragilis , and these drugs showed a high degree of activity against Haemophilus influenzae and Neisseria gonorrhoeae .