Comparative trial of norfloxacin and trimethoprim-sulfamethoxazole in the treatment of women with localized, acute, symptomatic urinary tract infections and antimicrobial effect on periurethral and fecal microflora.

Forty-three women with acute, symptomatic urinary tract infections were randomized to receive either norfloxacin (400 mg) twice daily or trimethoprim-sulfamethoxazole (160-800 mg) twice daily for 10 days. Of the 43 patients, 7 (16%) had low-count bacteriuria and pyuria and were included in the evaluation. Escherichia coli was isolated in 72% of the infections, whereas coagulase-negative staphylococci were isolated in 14%. All isolates were susceptible to the assigned study drug. The MICs for 90% of the strains susceptible to norfloxacin and trimethoprim-sulfamethoxazole were less than or equal to 2 and less than or equal to 0.8-16 micrograms/ml, respectively. The cure rates for norfloxacin and trimethoprim-sulfamethoxazole were 95 and 90%, respectively. There were 17 patients with presumptive upper tract infections; only 1 of these relapsed after therapy. The effects on the periurethral flora were similar in both groups, but the infecting organism was eradicated from the fecal flora in 93% of the patients treated with norfloxacin and in 57% of the patients treated with trimethoprim-sulfamethoxazole. More early reinfections occurred in the trimethoprim-sulfamethoxazole group, with resistant organisms appearing in urine and in the periurethral and fecal flora in all cases. Three patients in each group experienced adverse clinical effects, but these were more severe in the trimethoprim-sulfamethoxazole group. No adverse hematological or biochemical changes were noted. From these results, we concluded that norfloxacin is at least as effective as trimethoprim-sulfamethoxazole in the therapy of acute, symptomatic urinary tract infections in women.