In vitro antimicrobial activity of cefoperazone, cefotaxime, moxalactam (LY127935), azlocillin, mezlocillin, and other beta-lactam antibiotics against Neisseria gonorrhoeae and Haemophilus influenzae, including beta-lactamase-producing strains.

Minimum inhibitory concentrations and agar disk diffusion tests were determined on clinical isolates of beta-lactamase-positive and beta-lactamase-negative Neisseria gonorrhoeae and Haemophilus influenzae with the newer beta-lactam antibiotics, cefoperazone, cefotaxime, moxalactam (LY127935), azlocillin, mezlocillin, and piperacillin, and with seven older beta-lactam antibiotics. All the drugs were active against beta-lactamase-negative strains of N. gonorrhoeae and H. influenzae. The drug most active against beta-lactamase-positive N. gonorrhoeae was cefotaxime, followed closely by cefoperazone, moxalactam, piperacillin, and mezlocillin. The drugs most active against beta-lactamase-positive strains of H. influenzae were cefotaxime, moxalactam, cefoperazone, and cefamandole.