Comparison of mezlocillin and carbenicillin as therapy for various infectious diseases.

The efficacy and safety of mezlocillin, a new broad-spectrum semisynthetic penicillin, were compared with those of carbenicillin in a nonblind, controlled clinical study in 89 adult patients. The infections treated were primarily those of the urinary tract, skin, and gastrointestinal or hepatobiliary tract. Escherichia coli, Proteus mirabilis, Proteus morganii, and Pseudomonas aeruginosa were the causative organisms isolated most frequently. A complete resolution of signs and symptoms was achieved in 78% of the mezlocillin patients and in 71% of the carbenicillin patients. In the mezlocillin group, causative organisms were eliminated in 80% of the courses, and in the carbenicillin group the elimination rate was 86%. Two adverse reactions, rash and diarrhea, were reported in mezlocillin-treated patients; none were reported for the carbenicillin group.