Prevention of urinary tract infection.

Recurrent UTI remains an exceedingly common clinical problem among women of all ages. Among otherwise healthy premenopausal and postmenopausal women, increased susceptibility to recurrences seems to be conferred by intrinsic host factors, such as nonsecretor genotype or estrogen status, and by exogenous exposures or behaviors, such as use of a diaphragm with spermicide, antimicrobial use, and sexual behavior. The natural history of recurrent UTIs is notable for a temporal clustering phenomenon, the tendency of women to revert to a baseline infection pattern after the cessation of preventive interventions, and repeated serial reinfections of the urinary tract from the fecal reservoir, often by genetically identical organisms. Low-dose antimicrobial regimens given daily, three times weekly, or postcoitally are effective in preventing recurrences in most women with a predisposition to frequent infection. Intermittent patient-initiated self-treatment is an appropriate and effective option in some patients with lower recurrence rates. In postmenopausal women, estrogen replacement therapy, particularly vaginally applied estriol creams, may also significantly reduce the rate of recurrent UTI. Ongoing investigations in the areas of microbial ecology of the vaginal flora, the molecular basis for host-parasite interactions within the urinary tract, and vaccine development may eventually lead to improved means to prevent recurrent urinary tract infections more effectively.