Urinary tract infections (UTIs) are bacterial infections in the urinary system. They’re very common and usually not serious, though there can be exceptions.
Your urinary tract includes your bladder, kidneys, ureters (two tubes that go from your kidneys to your bladder), and urethra (how urine goes out of your body from your bladder).
If you have a UTI in your kidneys, doctors call it pyelonephritis. If it’s in your bladder, the medical term is cystitis.
Who Gets Urinary Tract Infections?
Anyone can. But UTIs are more likely if you:
- Are a woman
- Have had UTIs before
- Have a condition that affects your bladder's nerve supply (including diabetes, multiple sclerosis, Parkinson's disease, and spinal cord injuries)
- Have been through menopause
- Are overweight
- Have something that blocks the passage of urine, such as a tumor, kidney stone, or an enlarged prostate
- Use a contraceptive diaphragm or spermicide for birth control
- Have a catheter, a tube placed into the bladder to drain urine from the bladder into a bag outside the body
- Are a man who has sex with men, has HIV infection, or hasn’t been circumcised
Most of these traits also raise the chance that a simple bladder infection may become a more serious kidney infection, or turn into sepsis (an infection that has gotten into your bloodstream). For pregnant women, a kidney infection can raise the odds of delivering a baby too early.
Most UTIs are due to bacteria that are normally found in your gut, such as E. coli. Other bacteria that can cause them include staphylococcus, proteus, klebsiella, enterococcus, and pseudomonas.
Some bladder infections in both men and women are linked to two sexually transmitted bugs: Chlamydia trachomatis and mycoplasma. Another parasite, trichomonas, can cause similar symptoms.
Women are more likely to get urinary tract infections, because the tube that goes from the bladder to the outside (the urethra) is much shorter than in men. Because the urethral opening is closer to the anus in women, it’s easier for bacteria from stool to get into the female urethra. A urinary tract infection may be linked to sex.
In men, a bladder infection is almost always a symptom of another condition. Often, the infection has moved from the prostate or some other part of the body. Or it may mean that a tumor or something else is blocking or interfering with the urinary tract.
Chronic kidney infections in children sometimes happen because of a structural problem that allows urine to flow back from the bladder to the kidneys (reflux), or because the bladder doesn’t empty completely.