What Causes Urinary Tract Infections Among Older Adults?

A fellow caregiver asked...

What causes urinary tract infections (UTIs), and why are they so common among older adults?

Expert Answer

Dr. Leslie Kernisan is the author of a popular blog and podcast at BetterHealthWhileAging.net. She is also a clinical instructor in the University of California, San Francisco, Division of Geriatrics.

Older adults are prone to urinary tract infections (UTIs) because they tend to experience certain problems that set people up for this kind of infection. Experts estimate that 25 to 30 percent of all infections in older adults are UTIs.

The root cause of urinary tract infections is usually bacteria growing in the urine within the bladder; unlike the bowels, the bladder is supposed to be a sterile environment. Bacteria grow in the urine of the bladder when one has difficulty emptying the bladder -- a common scenario for older adults. If the bladder isn't emptied completely, urine remains there longer than normal and bacteria have more time to start growing.

Other reasons that older adults develop urinary tract infections include the following:

  • They tend to have generally impaired immunity, especially if they're frail.

  • Older men are more likely to have incomplete bladder draining due to prostate problems.

  • Postmenopausal women are more likely to have incomplete bladder draining due to bladder prolapse (when the bladder slips out of place) or cystocele (bulging of the bladder into the vagina).

  • Older people may retain urine due to anticholinergic medications (antihistamines, tricyclic antidepressants).

  • They're more likely to have bladder or bowel incontinence, which can lead to increased chances of contamination of the urethra (the canal through which urine exits the bladder).

  • They're more apt to get an indwelling catheter while hospitalized or in a nursing home.

It's important to know the signs of urinary tract infection in an older person and get prompt medical care.

Note: Both older men and older women are prone to UTIs. This is different among younger and middle-aged adults: in that age group, UTIs are much more common in women. That's because the pathway into a woman's bladder (the urethra) is short, so it's relatively easy for bacteria to get to the bladder. Both sexual activity and use of spermicides have also been linked to UTIs.