Evaluation of therapeutic efficacy of ureidopenicillins in comparison to sisomicin and cephalotin in experimental infections of rabbits.

The therapeutic efficacy of azlocillin, mezlocillin, cephalotin, and sisomicin was evaluated by experimental infection in rabbits. After one hour following infection with Escherichia coli, Klebsiella pneumoniae or Pseudomonas aeruginosa, antibiotics were applied intramuscularly. Colony-forming units were counted before the infection and every day thereafter. Leukocytosis was determined before infection and 3 and 7 days after initiation of therapy. Therapy with antibiotics was continued for seven days, rabbits sacrificed and CFU/g tissue determined. It was shown that in experimental infection caused by E. coli or K. pneumoniae in rabbits, sisomicin was most effective, followed by mezlocillin, azlocillin, and cephalotin. Efficacy of therapy against P. aeruginosa was as follows: sisomicin, azlocillin, mezlocillin.