Antimicrobial and Clinical Efficacy of Nitrofurantoin in the Treatment of Acute Lower Urinary Tract Infections in Adults

In the light of increasing resistance to antibio tics used for the treatment of acute urinary tract infections, nitrofurantoin currently experiences a renaissance. Nitrofurantoin shows good efficacy against most bacteria expected in urinary tract infection, and the development of resistance is low. A study on the antimicrobial and clinical efficacy of nitrofurantoin in the treatment of acute lower urinary tract infections was conducted in Mexico City, an area where resistance rates of uropathogens to trimethoprim/sulfamethoxazole (cotrimoxazole) are high. In this open-label, single-arm study 20 adult patients (18 females, 2 males) with positive urine culture were treated orally with nitrofurantoin sustained release 100 mg twice daily for 7 days. Urinary nitrofurantoin concentrations were determined at baseline and day 4 of the study. Primary endpoint was the antimicrobial efficacy of nitrofurantoin at 12 to 16 days after baseline, assessed by changes in urine culture results. In the patient population treated per protocol, primary endpoint analysis revealed a microbial eradication rate of 92.3%. At 35 to 42 days, the eradication rate was 83.3%. At these times, all patients in the per protocol population were free of symptoms. In patients with complicating factors, e.g. diabetic polyneuropathy, both antimicrobial and clinical efficacy appeared to be reduced. Urinary nitrofurantoin concentrations were mostly above minimum inhibitory concentrations of the isolated uropathogens. The study drug was generally well tolerated. Most frequent drug-related adverse event was mild headache, occurring in 10.8% of patients. Two patients discontinued the study due to rash. The results of the present study indicate good antimicrobial and clinical efficacy of nitrofurantoin in the treatment of acute uncomplicated urinary tract infections as well as acceptable tolerability in adults.