- Take the UTI Quiz
- Urinary Tract Infection (UTI) - Slideshow
- Urinary Incontinence in Women - Slideshow
- Urinary Tract Infection (UTI) in Adults FAQs
- Patient Comments: Urinary Tract Infections - Symptoms
- Patient Comments: Urinary Tract Infections - Treatments
- Patient Comments: Urinary Tract Infections - Experience
- Patient Comments: Urinary Tract Infections - Home Remedies
- Patient Comments: Urinary Tract Infections - Medications
- What is a urinary tract infection (UTI)?
- What causes a urinary tract infection?
- Are urinary tract infections contagious?
- What are urinary tract infection symptoms and signs?
- When should people seek medical care for a UTI?
- How do physicians diagnose a urinary tract infection?
- What kinds of doctors treat urinary tract infections?
- Are there home remedies for a urinary tract infection?
- What is the treatment for a urinary tract infection?
- What follow-up is needed for a urinary tract infection?
- Is it possible to prevent a urinary tract infection?
- What is the prognosis of a urinary tract infection?
Quick GuideUrinary Tract Infection (UTI) Pictures Slideshow: Bladder Infection Symptoms, Causes and Treatments
What causes a urinary tract infection?
The urine is normally sterile. An infection occurs when bacteria get into the urine and begin to grow. The infection usually starts at the opening of the urethra where the urine leaves the body and moves upward into the urinary tract.
- The culprit in at least 90% of uncomplicated infections is a type of bacteria called Escherichia coli, better known as E. coli. These bacteria normally live in the bowel (colon) and around the anus.
- These bacteria can move from the area around the anus to the opening of the urethra. The two most common causes of this are improper wiping and sexual intercourse.
- Usually, the act of emptying the bladder (urinating) flushes the bacteria out of the urethra. If there are too many bacteria, urinating may not stop their spread.
- The bacteria can travel up the urethra to the bladder, where they can grow and cause an infection.
- The infection can spread further as the bacteria move up from the bladder via the ureters.
- If they reach the kidney, they can cause a kidney infection (pyelonephritis), which can become a very serious condition if not treated promptly.
The following people are at increased risk of urinary tract infection:
- People with conditions that block (obstruct) the urinary tract, such as kidney stones
- People with medical conditions that cause incomplete bladder emptying (for example, spinal cord injury)
- Postmenopausal women: Decreased circulating estrogen makes the urinary tract more vulnerable to a UTI.
- People with suppressed immune systems: Examples of situations in which the immune system is suppressed are HIV/AIDS and diabetes. People who take immunosuppressant medications such as chemotherapy for cancer also are at increased risk.
- Women who are sexually active: Sexual intercourse can introduce larger numbers of bacteria into the bladder. Urinating after intercourse seems to decrease the likelihood of developing a urinary tract infection.
- Women who use a diaphragm for birth control
- Men with an enlarged prostate: Prostatitis or obstruction of the urethra by an enlarged prostate can lead to incomplete bladder emptying, thus increasing the risk of infection. This is most common in older men.
- Males are also less likely to develop UTIs because their urethra (tube from the bladder) is longer.
- Breastfeeding has been found to decrease the risk for urinary tract infections in children.
The following special groups may be at increased risk of urinary tract infection:
- Very young infants: Bacteria gain entry to the urinary tract via the bloodstream from other sites in the body.
- Young children: Young children have trouble wiping themselves and washing their hands well after a bowel movement. Poor hygiene has been linked to an increased frequency of urinary tract infections.
- Children of all ages: Urinary tract infection in children can be (but is not always) a sign of an abnormality in the urinary tract, usually a partial blockage. An example is a condition in which urine moves backward from the bladder up the ureters (vesicoureteral reflux).
- Hospitalized patients or nursing-home residents: Many of these individuals are catheterized for long periods and are thus vulnerable to infection of the urinary tract. Catheterization means that a thin tube (catheter) is placed in the urethra to drain urine from the bladder. This is done for people who have problems urinating or cannot reach a toilet to urinate on their own.
- Patients using catheters: If a patient is required to empty their bladder using a catheter, they are at increased risk for infection.
Are urinary tract infections contagious?
No. Urinary tract infections (UTIs) are not contagious.