This is a complicated question, and a good one. I'll to simplify the answer. There are several reasons why women are at a higher risk of urinary tract infections (UTI)
as they age.
Urine retention or incomplete bladder emptying: As women get older their bladders may not empty as efficiently, leaving urine behind. This urine can become contaminated with bacteria, which leads to infection. Many things can contribute to urine retention. These include: Gynecological problems (organ prolapse, surgeries), urethral stricture, severe constipation, medication side effects, and neurological diseases like strokes and Parkinson’s disease. In particular, bladder medications used to treat incontinence can cause urine retention. What helps? Talk to a doctor or pharmacist about changing medications. Treat constipation.
Decreased ability to fight infection: After menopause, changes can occur in normal vaginal bacteria. For example, lactobacillus, a healthy and protective bacterium decreases. This decrease allows the more troublesome fecal bacteria to over-grow, which can cause infection. What helps? Check with a gynecologist and good hygiene.
Female anatomy: With women, the urethra (where urine comes from) is only a couple of inches from the rectum (where fecal infection-causing bacteria come from), so it's easy for baceria to spread. As some women age, they lose the ability to toilet efficiently. If someone is incontinent and wears diapers, it's more challenging. What helps? Women should always wipe from the front to the back. Frequent diaper changes and cleaning.
Dietary changes: Many elders do not drink enough, as they're afraid of urine accidents, can't access beverages independently, or can't express or feel "thirst" as clearly as before (especially true for women with dementia). What helps? Drinking at least eight glasses of water or clear fluid daily. Cranberry juice may also help, though the research on this is inconclusive. I's recommend trying one 8 oz. glass of 100% cranberry juice twice daily. If the frequent UTIs continue, then I'd stop.
If you know a woman who gets frequent urinary tract infections, she should see her doctor who can check for and address these issues.