Duration of treatment of urinary tract infections.

This review was stimulated by the current interest in use of single-dose therapy for uncomplicated "lower tract" infection in females and the potential benefit of long-term prophylaxis for patients with recurrent infections. Duration of therapy is only a tactic. It is dependent on understanding the natural history of urinary tract infections in relation to risk factors and the predictable response to treatment. Based on the pertinent literature, a series of elements are presented that define the current consensus concerning the definition, natural history and risk of renal damage from urinary tract infection. These are then considered in relation to the current diagnostic measures and procedures to localize infection. Single-dose therapy combined with bacteriologic monitoring appears to be a useful method to localize infection. Although it defines individuals who may require more prolonged treatment, it has not yet been shown to predict risk of renal damage or identify a subpopulation requiring further study. The major predictors of renal injury are anatomic and neurologic lesions that alter urine flow and host factors that decrease resistance to infection. These are currently better defined by individual patient characteristics and clinical observation than by localization studies. Long-term low-dose prophylaxis has been shown to be an effective means of management of highly recurrent episodes of infection. It does not, however, appear to prevent recurrences, after therapy has been discontinued, even after periods of prophylaxis as long as six months. Treatment should be based on reasonable expectancy of reduction in morbidity and/or renal damage.