Validity of urinary catheter specimen for diagnosis of urinary tract infection in the elderly.

Twenty elderly nursing home patients with long-term indwelling bladder catheters were studied to evaluate the validity of the microbiology of urine samples obtained from catheters that had not been changed for at least 30 days. Paired urine samples from "old" catheters and newly inserted catheters were compared for quantitative and qualitative microbiology. Urine microbiology for old catheters was highly sensitive but had poor specificity.