Randomised controlled trial of nitrofurantoin versus placebo in the treatment of uncomplicated urinary tract infection in adult women.

BACKGROUND: Urinary tract infections (UTIs) are very common and have been treated with apparent success with antimicrobials for many years. However, there is a paucity of placebo-controlled clinical trials.

AIM: To measure the symptomatic and bacteriological short-term effect of nitrofurantoin treatment versus placebo, in the treatment of uncomplicated UTI in adult non-pregnant women.

DESIGN OF STUDY: Randomised placebo-controlled trial in general practice.

SETTING: Non-pregnant women, aged between 15 and 54 years old, consulting a general practitioner for symtoms suggestive of uncomplicated lower UTI and with pyuria (positive for leucocyte esterase test).

METHOD: A dipslide was inoculated in first-void midstream urine and sent for examinion. The patients were randomised to receive nitrofurantoin 100 mg or placebo four times daily for three days. After three, seven, and 14 days a new dipslide was inoculated and symptoms of UTI were checked or improvement of symptoms and bacteriuria.

RESULTS: Of 166 women consulting with symptoms suggestive for UTI, 78 had pyuia and agreed to participate in the study (the clinically suspected UTI group); of these, 40 received nitrofurantoin and 38 received placebo. The result for combined symptomatic improvement and cure after three days was 27/35 in the nitrofurantoin group and 19/35 in the placebo group (c2 with Yates' correction P = 0.008; number needed to treat [NNT] = 4.4, 95% confidence interval [CI] = 2.3 to 79). After seven days, combined improvement and cure was observed in 30/34 and 17/33 respectively (P = 0.003, NNT = 2.7, 95% CI = 1.8 to 6.0). At inclusion, 56 women had bacteriuria of > or = 10(5) CFU/ml (the bacteriologically proven UTI group). Of these, 29 received nitrofurantoin and 27 received placebo. After three days the bacteriological cure was 21/26 in the treatment group, compared with 5/25 in the placebo group (P < 0.001; NNT = 1.6, 95% CI= 1.2 to 2.6). After seven days the bacteriological cure rate was 17/23 in the intervention group and 9/22 in the placebo group (P = 0.05, NNT = 3, 95% CI = 1.7 to 17).

CONCLUSION: In women with bacteriologically proven UTI, nitrofurantoin was significantly more effective than placebo in achieving bacteriological cure and symptomatic relief in just three days; this was still present after seven days. In patients with clinically suspected UTI the symptomatic effect was statistically significant after