Comparative efficacy and safety of nalidixic acid versus trimethoprim/sulfamethoxazole in treatment of acute urinary tract infections in college-age women.

One hundred and thirty-five college-age women with acute urinary tract infections caused by gram-negative Enterobacteriaceae were treated by random allocation with either nalidixic acid (NA), 1 g every 6 h for 7 days, or trimethoprim/sulfamethoxazole (TMP/SMZ), 160/800 mg every 12 h for 10 days. The clinical and bacteriological cure rates were 98.0% in each group on the last day of therapy. At 1 and 4 week posttherapy, both the clinical and bacteriological cure rates for NA declined to 90.0 and 74.0% respectively; for TMP/SMZ, they declined to 93.0 and 72.0% respectively. By 4 weeks posttherapy, 96.0% of the TMP/SMZ group and 93.0% of the NA group had remained free of the initial urinary pathogens. Neither drug was associated with emergence of resistant bacterial mutants in urine. The antibody-coated bacteria tested (ACBT) localized 31.5% of the infections of the kidney and 67.7% to the bladder. Upper tract symptoms did not correlate with the presence of a positive ACBT. The response to therapy was similar for the two regimens regardless of ACBT results. After treatment, the emergence of resistant Enterobacteriaceae in fecal flora was 1.1% in the NA group and 2.3% in the TMP/SMZ group. The incidences of drug reactions were 7.0% with NA and 6.3% and TMP/SMZ.