Introduction & Objective: Urinary tract infections (UTI) are a common cause of morbidity and its diagnosis and treatment can lead to health. In this study we evaluated the efficacy of the long- term low-dose antibiotic prophylaxis with Cotrimoxazole and Nalidixic-acid in the patients with recurrent UTI.

Materials & Methods: This study is a before and after clinical trial without control group done on 100 patients with recurrent UTI who had referred to Ekbatan Hospital. These patients had no urologic findings in clinical and para-clinical evaluations. These patients were treated by Cotrimoxazole or Nalidixic-acid in long term-low dose Antibiotic prophylaxis method according to urine culture and antibiogram. These patients followed with urine cultures in the therapeutic and 6 month follow-up periods. Also, we evaluated the differences between age, gender, type of microorganism, marital status, re-infection time and number of recurrences before treatment.

Results: Our study includes 100 patients (83% female and 17% male). The mean+/-SD age of the patients in the group treated with Cotrimoxazole (group A) was 15.57+/-13.03 and in the patients treated with Nalidixic-acid (group B) was 13.67+/-10.9 years. 74% of the patients who were treated with Cotrimoxazole were single and this number was 66% for the nalidixic-acid group. E.coli, kelebsiella and proteous account for 80%, 18% and 2% of infections in the Cotrimoxazole group, respectively. These microorganisms account for 62%, 34% and 4% of infections in the nalidixic-acid group respectively. The re-infection rate for the Cotrimoxazole group was 18% which 82% of them were successfully treated. The re-infection rate for nalidixic-acid was 12% which 88% of them showed a good response to nalidixic-acid. In fact, in this study Nalidixic-acid was as effective as Cotrimoxazole.

Conclusion: The long term-low dose antibiotic prophylaxis is very effective in the treatment of recurrent UTI and in our study Nalidixic-acid efficacy was similar to Cotrimoxazole.