The urinary tract is usually sterile. Asymptomatic bacteriuria or asymptomatic UTI is a microbiological diagnosis defined as "the isolation of a specified quantitative count of bacteria in an appropriately collected urine specimen obtained from a person without symptoms or signs referable to urinary infection." The specimen should be optimally collected to prevent bacterial contamination. When possible, voided midstream urine is the preferred specimen in adults; however, it necessitates a good micturition control and adequate volume in the bladder. This can be problematic for many older adults. A clean-catch can be obtained from men or women, but it can be difficult in the context of LTC. Other acceptable collection techniques include a freshly applied condom catheter for men and in-and-out catheterization, although a risk of inducing a UTI exists with the latter method. Catheter specimens should be aspirated directly from the catheter using a sterile needle and placed in a sterile container. Unacceptable specimens include bedpan urine and bags because of the increased risk of contamination.[3,12] Transport to the laboratory should be timely.
According to the Infectious Diseases Society of America 2005 guidelines, the quantitative definition of asymptomatic bacteriuria is as follows: for women, isolation of the same bacterial species with a quantitative count of ≥105 CFU/mL in two consecutive voided urine specimens; for men, isolation of one bacterial species with a quantitative count of ≥105 CFU/mL in one voided urine specimen; or isolation of one bacterial species isolated with a quantitative count of ≥102 CFU/mL in a single catheterized urine specimen for men or women.
Asymptomatic bacteriuria is common among older adults and practically universal among those with indwelling catheters. The prevalence in healthy older women living in the community is around 20%, and in men >75 years old is 6-15%. In LTC facilities, the percentages are even higher: 25-50% in women and 15-40% in men. The rise in prevalence parallels the increase in comorbidities, especially neurological, associated with micturition problems.[3,7]
The recommendations by the Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America are clear concerning asymptomatic bacteriuria in the older population, whether residing in the community or in LTC facilities: routine screening and treatment are not recommended. There have been several studies[13,14,15,16] showing no benefits associated with the treatment of asymptomatic infections as measured in the rate of subsequent symptomatic infections, improvement of chronic urinary symptoms, or survival. Moreover, some harm can be caused, mostly associated with side effects of antimicrobials and increased resistance in uropathogens.[3,4,11]
It is to be noted that pyuria is common among persons with asymptomatic bacteriuria. This seems to reflect the fact that asymptomatic bacteriuria is more than mere colonization: there is an immune response associated with the presence of a significant amount of bacteria in the urinary tract. Among older adults in LTC facilities, 90% of those with bacteriuria, 30% of those without bacteriuria, and 50-100% of those with an indwelling catheter have pyuria.[3,4,17,18,19] In this context, the presence of pyuria is not an indication for treatment.
Geriatrics and Aging. 2008;11(10):582-588. © 2008 1453987 Ontario, Ltd.
Cite this: Urinary Tract Infections in Older Adults: Current Issues and New Therapeutic Options - Medscape - Nov 01, 2008.