Definition of Urinary tract infection - adults:

A urinary tract infection, or UTI, is an infection that can happen anywhere along the urinary tract. Urinary tract infections have different names, depending on what part of the urinary tract is infected.

• Bladder -- an infection in the bladder is also called cystitis or a bladder infection
• Kidneys -- an infection of one or both kidneys is called pyelonephritis or a kidney infection
• Ureters -- the tubes that take urine from each kidney to the bladder are only rarely the site of infection
• Urethra -- an infection of the tube that empties urine from the bladder to the outside is called urethritis

See also:

• Cystitis - noninfectious
• Interstitial cystitis
• Urethritis
• Urinary tract infection - children

Causes, incidence, and risk factors:

Urinary tract infections are caused by germs, usually bacteria that enter the urethra and then the bladder. This can lead to infection, most commonly in the bladder itself, which can spread to the kidneys.

Most of the time, your body can get rid of these bacteria. However, certain conditions increase the risk of having UTIs.

Women tend to get them more often because their urethra is shorter and closer to the anus than in men. Because of this, women are more likely to get an infection after sexual activity or when using a diaphragm for birth control. Menopause also increases the risk of a UTI.

The following also increase your chances of developing a UTI:

• Diabetes
• Advanced age (especially people in nursing homes)
• Problems emptying your bladder (urinary retention) because of brain or nerve disorders
• A tube called a urinary catheter inserted into your urinary tract
• Bowel incontinence
• Enlarged prostate, narrowed urethra, or anything that blocks the flow of urine
• Kidney stones
• Staying still (immobile) for a long period of time (for example, while you are recovering from a hip fracture)
• Pregnancy