A comparative study of the efficacy and safety of azlocillin and gentamicin in the treatment of serious infections.

Azlocillin, a new semisynthetic ureidopenicillin, has increased in-vitro activity against Pseudomonas aeruginosa and good activity against other Gram-negative organisms. In a comparative clinical study, azlocillin was administered intravenously at 18 g/day to 24 patients and gentamicin intramuscularly at 3 to 5 mg/kg/day to 25 patients, most of whom had infections of the skin and skin structure, intra-abdominal cavity, or lower respiratory tract. Gram-negative organisms, usually Ps. aeruginosa or Escherichia coli, and Staphylococcus aureus, were isolated most frequently. At the end of therapy, 18/24 (75%) of the patients with one infection site had an excellent clinical response after azlocillin, as compared with 7/20 (35%) after gentamicin (P = 0.014). The overall response to treatment was cure in 17/24 (70.8%) of the azlocillin patients and 9/24 (37.5%) of the gentamicin patients (P = 0.042). Bacteriological response was in the azlocillin group 28/33 or 84.8% as compared to the gentamicin group 38/51 or 74.5%.