Fosfomycin versus ampicillin in the treatment of acute pyelonephritis.

In a controlled open study of 38 patients with acute pyelonephritis, treatment with fosfomycin 8 g b.i.d. was compared to treatment with ampicillin 2 g t.i.d., both for one week. The most common pathogen in both groups was Escherichia coli, susceptible to fosfomycin. However, 17% were resistant to ampicillin. The success rate was 44% in the fosfomycin treated group and 28% in the ampicillin group. The difference was not significant (p greater than 0.20). Peak concentrations of fosfomycin in serum were 395 mg/l and in tissue fluid 85 mg/l. Urine concentrations ranged from 6990 to 24,320 mg/l.