Epidemiology of asymptomatic bacteriuria in elderly women.

We studied asymptomatic bacteriuria in elderly ambulatory women residents without indwelling catheters in self-contained apartment houses at the Philadelphia Geriatric Center (PGC), in the nursing home at PGC, and in several life-care communities (LCC). Subjects were studied every 6 months from January 1983 through January 1989, and since enrollment was continuous some participated in more surveys than others. PGC residents were middle class and lived either in a self care apartment house (CL) or nursing home (NH); LCC residents were middle or upper class. Antimicrobial therapy for asymptomatic bacteriuria was not given by the study team. The ages of the 865 women studied averaged 80.3, 82.8, and 83.3 years in LCC, CL, and NH, respectively. On each survey about 11% at LCC, 18% at CL, and 25% at NH sites had positive cultures. Turnover was high. The conversion rate from a negative to a positive culture was 5% at LCC, 11% at CL, and 8% at NH. The reversion rate from a positive to a negative culture was 33% at LCC, 34% at CL and 31% at NH (P greater than 0.05). Persistent infection with the same organism was uncommon. Infection risk was associated with residence, which was partially explained by a factor evaluating mobility, but was unrelated to age or scores evaluating activities of daily living or mental status. Besides mobility, other more complex factors play a role in the acquisition of infection.