Activity of aztreonam and new beta-lactam antibiotics against penicillinase-producing Neisseria gonorrhoeae

The susceptibilities of a group of penicillinase-producing and none-penicillinase-producing isolates of Neisseria gonorrhoeae were determined to the monobactam aztreonam, four third-generation cephalosporins, and three second-generation cephalosporins. Aztreonam and the third-generation cephalosporins were highly active against both penicillin-resistant and penicillin-susceptible strains. MIC₉₀s for penicillin-resistant isolates were the same as or not more than fourfold higher than for penicillin-susceptible strains. Ceftizoxime and defotaxime were the most active of the compounds tested; aztreonam, deftrazidime, moxalactam, and defuroxime were somewhate less active and had activities similar to another. Cefoxitin and cefamandole were the least active antibiotics tested.