Cefoperazone is primarily bactericidal; it also may be bacteriostatic. Activity depends on the organism, tissue penetration, dosage, and rate of organism multiplication. Drug acts by adhering to bacterial penicillin-binding proteins, thereby inhibiting cell wall synthesis. Third-generation cephalosporins appear to be more active against some beta-lactamase-producing gram-negative organisms. Cefoperazone is active against some gram- positive organisms and many enteric gram-negative bacilli, including Streptococcus pneumoniae and Streptococcus pyogenes, Staphylococcus aureus (penicillinase- and non- penicillinase-producing), Staphylococcus epidermidis, Escherichia coli, Klebsiella, Haemophilusinfluenzae, Enterobacter, Citrobacter, Proteus, some Pseudomonas species (including Pseudomonasaeruginosa), and Bacteroides fragilis. Acinetobacter and Listeria usually are resistant. Cefoperazone is less effective than cefotaxime or ceftizoxime against Enterobacteriaceae but is slightly more active than those drugs against Pseudomonas aeruginos