ABSTRACT
Cefoperazone (10 mg/kg) and cephalothin (20 mg/kg) administered intramuscularly every 6 h were both effective in reducing the number of Staphylococcus aureus cells in vegetations in rabbits with endocarditis. Cefoperazone produced higher peak concentrations and greater bactericidal activity in serum than did cephalothin. Cefoperazone (40 mg/kg) administered every 6 h was significantly more effective than cefamandole (40 mg/kg) administered every 6 h in reducing the number of Enterobacter aerogenes cells in vegetations. Although cefamandole produced higher peak concentrations in serum, the serum bactericidal activity was greater with cefoperazone. The half-lives in serum were 0.64 h for cefoperazone and 0.46 h for cephalothin and cefamandole.