Asymptomatic Bacteriuria in Older Adults

Urinary tract infection is the most frequent infection that occurs in older populations, and most urinary infection is asymptomatic. The terms asymptomatic bacteriuria and asymptomatic urinary tract infection are generally used interchangeably, both defined as a urine specimen that meets microbiologic criteria for urinary tract infection in an individual with no symptoms or signs attributable to infection. Growth of ≥ 108cfu/L (≥ 105cfu/mL) of the same organism(s) on two consecutive urine specimens identifies asymptomatic bacteriuria.1 In community-living women, the prevalence of asymptomatic bacteriuria increases with age, approaching 10–20% among women older than 80 years (Table 1).2 For men, asymptomatic bacteriuria is uncommon prior to 60 years of age, while about 5% of men older than 70 years have a positive urine culture. Thus, in the community one in every five to 10 older women and one in every 10 to 20 older men have bacteriuria. The prevalence of asymptomatic bacteriuria in residents of long-term care facilities is extremely high (Table 1).2 Among institutionalized women and men, 25–50% and 15–40%, respectively, have a positive urine culture at any time. For the individual nursing home resident, increased functional impairment as evidenced by incontinence of urine or bowel and dementia is strongly associated with the presence of bacteriuria.2 Those residents of long-term care facilities with voiding managed with indwelling catheters (5–10%) comprise a unique group.3 A chronic indwelling catheter (i.e., one in place for 30 days or longer) is uniformly associated with persistent polymicrobial bacteriuria.4 Thus, residents with chronic indwelling catheters should be considered bacteriuric at all times.