Comparison of in vitro activities of eight beta-lactamase-stable cephalosporins against beta-lactamase-producing gram-negative bacilli.

In vitro activities of eight beta-lactamase-stable cephalosporins, cefoxitin, cefuroxime, cefotaxime, moxalactam, SCE-1365, cefoperazone, ceftazidime, and cefsulodin, were compared against selected cephalothin-resistant or beta-lactamase-producing gram-negative bacilli or both. SCE-1365, cefotaxime, moxalactam, and ceftazidime had very similar activities against Enterobacteriaceae; SCE-1365 displayed the highest activity, and ceftazidime displayed the lowest activity. These four antibiotics were about 20 times more active than cefoperazone and 50 to 100 times more active than cefoxitin and cefuroxime. Against Pseudomonas aeruginosa and the other Pseudomonas species, ceftazidime showed the highest activity by far, followed by cefsulodin and cefoperazone. A close parallel resistance against P. aeruginosa isolates was observed between piperacillin on the one hand and cefoperazone and cefsulodin on the other.