Comparative in vitro activity of 8 cephalosporins on 109 strains of Neisseria gonorrhoeae and 60 strains of Neisseria meningitidis.

The in vitro activity of 8 cephalosporins - cephalothin, cefamandole, cefoxitin, cefuroxime, cefotaxime, cefoperazone, moxalactam and ceftriaxone (Rocephin) was studied on 109 strains of Neisseria gonorrhoeae and 60 strains of Neisseria meningitidis, isolated from pathological material. Determination of the MICs of these antibiotics by an agar dilution method shows that on N. gonorrhoeae ceftriaxone (geometric mean of the MICs: 0.0008 microgram/ml) is the most active, followed by cefotaxime (0.001 microgram/ml); cefoperazone (0.008 microgram/ml) and moxalactam (0.01 microgram/ml) are one-tenth as active; then come cefuroxime (0.05 microgram/ml), cefamandole (0.10 microgram/ml) and finally cephalothin (0.26 microgram/ml) and cefoxitin (0.26 microgram/ml). The least susceptibility to penicillin and, to a greater degree, the production of beta-lactamase (8 strains) affect the level of susceptibility to these cephalosporins, but the MICs always remain relatively low.