Antibacterial activity of ceftizoxime, a beta-lactamase-stable cephalosporin

The in vitro activity of ceftizoxime was compared with that of other beta-lactam antibiotics against 538 isolates. Ceftizoxime was the most active agent tested against Escherichia coli and Klebsiella, inhibiting 80% at 0.025 microgram/ml. It was more active than cefotaxime against Enterobacter cloacae and E. aerogenes. Ceftizoxime was more active than cefoxitin, cefotaxime, cefoperazone, and carbenicillin against Proteus mirabilis and indole-positive Proteus. It inhibited 97% of multiresistant Serratia isolates at 12.5 microgram/ml, whereas cefotaxime inhibited only 19%. Ceftizoxime was less active than cefotaxime and cefoperazone against Pseudomonas aeruginosa, but was more active than carbenicillin. It was more active than cefotaxime and cefoxitin against Bacteroides. It was not appreciably destroyed by beta-lactamases of Staphylococcus aureus, Enterobacteriaceae, or Pseudomonas.