In vivo activity of ceftriaxone (Ro 13-9904), a new broad-spectrum semisynthetic cephalosporin.

Ceftriaxone (Ro 13-9904) was compared with other newer beta-lactam antibiotics for activity in experimental infections of mice with Enterobacteriaceae, Haemophilus influenzae, Pseudomonas aeruginosa, and gram-positive bacteria. Overall, ceftriaxone was equal or superior to cefotaxime and cefoperazone against systemic infections. All three drugs were highly potent against most organisms but were considerably less active against P. aeruginosa. However, ceftriaxone tended to be more active than the other two agents against 8 of the 10 P. aeruginosa strains tested. Ceftriaxone, cefmenoxime (SCE 1365), and moxalactam were all highly active against systemic infections with 16 strains of Enterobacteriaceae, whereas ceftriaxone was more active against infections with two strains of streptococci. When the drugs were administered at various time intervals before infection, ceftriaxone was superior to cefotaxime, cefmenoxime, and moxalactam. This suggested that ceftriaxone might be eliminated from mice more slowly than the other drugs. In the case of cefotaxime, this was directly confirmed by microbiological assays of plasma samples. In a murine meningitis model induced by Klebsiella pneumoniae or Streptococcus pneumoniae, ceftriaxone was more active than ampicillin or cefotaxime. Ceftriaxone was more active than ampicillin, cefotaxime, piperacillin, cefamandole, or carbenicillin in a pneumococcal, pneumonia model in mice. These studies indicate that ceftriaxone is a potent, broad-spectrum cephalosporin with unusual pharmacokinetic properties.