A prospective study of asymptomatic bacteriuria in sexually active young women

Background: Asymptomatic bacteriuria is common in young women, but little i s known about its pathogenesis, natural history, risk factors, and temporal association with symptomatic urinary tract infection. Methods: We prospectively evaluated 796 sexually active, nonpregnant women from 18 through 40 years of age over a period of six months for the occurre nce of asymptomatic bacteriuria (defined as at least 10(sup 5) colony-formi ng units of urinary tract pathogens per milliliter). The women were patient s at either a university student health center or a health maintenance orga nization (HMO). Periodic urine cultures were taken, daily diaries were kept , and regularly scheduled interviews were performed. Escherichia coli strai ns were tested for hemolysin, the papG genotype, and the ribosomal RNA type . Results: The prevalence of asymptomatic bacteriuria (the proportion of urin e cultures with bacteriuria in asymptomatic women) was 5 percent (95 percen t confidence interval, 4 percent to 6 percent) among women in the universit y group and 6 percent (95 percent confidence interval, 5 percent to 8 perce nt) among women in the HMO group. Persistent asymptomatic bacteriuria with the same E. coli strain was rare. Symptomatic urinary tract infection devel oped within one week after 8 percent of occasions on which a culture showed asymptomatic bacteriuria, as compared with 1 percent of occasions when asy mptomatic bacteriuria was not found (P<0.001). Asymptomatic bacteriuria was associated with the same risk factors as for symptomatic urinary tract inf ection, particularly the use of a diaphragm plus spermicide and sexual inte rcourse. Conclusions: Asymptomatic bacteriuria in young women is common but rarely p ersists. It is a strong predictor of subsequent symptomatic urinary tract i nfection. (N Engl J Med 2000;343:992-7.) (C) 2000, Massachusetts Medical So ciety.