Urinary tract infections (UTIs) and dementia

5. What can cause a urinary tract infection?

Urine is normally sterile (does not contain bacteria), although in older people it is common to have bacteria in the urine (known as bacteriuria). This is because the flow of their urine is weaker and they are less likely to empty their bladder fully. Using a catheter (a tube placed into the bladder that empties urine into a bag) almost always results in bacteria being present in the urine. This does not usually need treating unless the person starts to show symptoms of a UTI (see ‘Types of UTI and how they are treated’ below), when prompt treatment with antibiotics is important.

It is more common for women to get UTIs because the urethral opening is close to the vagina and anus. Poor hygiene and wiping ‘back to front’ (rather than front to back) after going to the toilet can enable bacteria from the bowel and vagina to enter the urethral opening to the bladder more easily. Sexual intercourse (and to a lesser extent other sexual activity) can also lead to UTIs in some people, though the risk is much greater for women.

As dementia progresses, it may be harder to maintain personal hygiene (for example, washing regularly, changing clothes). This may increase the risk of developing a UTI.

Abnormal changes in the structure of the urinary tract can lead to bladder emptying problems that may contribute to a UTI. These include an enlarged prostate in men or a prolapse in women (where the uterus, bladder or bowel descends from the normal position due to a weakness of the supporting structures).

Urinary catheters are a common cause of UTIs and must be avoided whenever possible. Urinary tract infections are the most common hospital-acquired infection in the UK. They account for a quarter of all hospital-acquired infections, and the majority of these are associated with catheters. Therefore, catheters should only be used for incontinence when all other options have been explored (see also ‘Catheter-related UTIs’ below).

Individuals with a weak immune system, for example people with diabetes or those being treated for cancer with chemotherapy, are at greater risk of getting a urinary tract infection.