Urinary tract infections with low and high colony counts in young women: Spontaneous remission and single-dose vs multiple-day treatment

Background: The aim of this study was to test whether the spontaneous cure rate is higher in dysuric women with low urinary colony counts (10² to 10⁴ colony-forming units [cfu] per milliliter) than in women with high colony counts (≥10⁵ cfu/mL) and whether the response of patients with low colony counts to single-dose treatment is better than those with high colony counts. Methods: Dysuric women underwent a clinical interview, examination, urine culture, and microscopic examination of urine, and were asked to postpone treatment or 2 days. At that time, the urine tests were repeated. Women with bacterial urinary tract infection were randomized to a group given a single dose of 1200 mg of norfloxacin and to a group treated with 400 mg of norfloxacin twice daily for 7 days. Cure rates were tested at 1 and 5 weeks after treatment. Results: Of 146 women with urinary tract complaints, 113 (25 patients with sterile urine cultures, 21 with low colony counts, and 67 with high colony counts) agreed to postpone antibiotic treatment. Two days after the initial urine culture, only one patient with a low initial colony count had a sterile urine culture (5%, 95% confidence interval, 0% to 14%); and 10 patients (48%, 95% confidence interval, 27% to 69%) had a colony count of 10 cfu/mL or more. The rate of spontaneous cure in women with high initial colony count was 7%, 95% confidence interval, 1% to 13%. One week after treatment, the cure rates were 48 (84%) of 57 patients given single-dose treatment vs 49 (98%) of 50 patients treated for 7 days. Five weeks after treatment the rates were 63% and 83%, respectively. The efficacy of single- dose treatment in patients with low urinary counts was similar to those with high counts, and less than that achieved by 7 days of treatment. Conclusions: The spontaneous cure rate for a 2-day period is minimal in patients with both a low and a high colony count, but half of the patients with low urinary counts will have high colony counts after this interval. The response to single-dose treatment is similar in patients with low and high colony counts, and lower than with multiday treatment.