The natural history of symptomatic recurrent bacteriuria in women.

In 23 adult women having uncomplicated recurrent urinary tract infections treated with 10 days of appropriate antibiotic for each infection, the following findings were noted. 1. The attack rate was 0.17 infections per month. 2. 94% of infections has associated symptoms. 3. 73% of symptomatic episodes had an associated infection. 4. 21% of infections had less than 10(5) bacteria per ml. 5. 34% of all infections were followed by an infection-free interval of at least six months and averaged 12.8 months. All but one patient had at least one infection-free interval. 6. Long infection-free intervals were followed by further infections; a remission is not a cure. 7. Between infection-free intervals the infections tended to occur in clusters with an attack rate of 0.47 infections per month. 8. Prophylaxis is less costly if begun at the second infection within a six-month period.