A urinary tract infection (UTI) is an infection of any part of the urinary system.2 Most infections involve the lower urinary tract. The urinary tract is comprised of the bladder, kidneys, ureters and urethra.
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1 Bladder -- An infection in the bladder is also called cystitis or a bladder infection. 2  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 rarely the only site of infection.
https://medlineplus.gov/ency/article/000521.htm
Urinary tract infection - adults. A urinary tract infection, or UTI, is an infection of the urinary tract. The infection can occur at different points in the urinary tract, including: Bladder -- An infection in the bladder is also called cystitis or a bladder infection.
https://medlineplus.gov/ency/article/000521.htm
Quick GuideUrinary Tract Infections (Bladder Infection): UTI Symptoms, Treatment, Causes. 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.
http://www.medicinenet.com/urinary_tract_infection/page2.htm
Symptoms of urinary tract infections146. The symptoms of a urinary tract infection can depend on age, gender, the presence of a catheter and what part of the urinary tract has been infected. Abdominal pains are a common symptom of urinary tract infections.
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Urinary Tract Infection: Causes, Symptoms and Treatments. The urinary tract is a system in the body for removing waste and excess water.1 It consists of the bladder, the kidneys, the ureters and the urethra.
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1 Urinary tract infections are commonly treated with antibiotics, although antibiotic use is also a risk factor for UTI.  Having diabetes increases the risk of UTI, as do the use of tampons and spermicides, frequent or intense sex, and sex with a new partner and/or multiple partners.
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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).
http://www.medicinenet.com/urinary_tract_infection/page2.htm
Urinary tract infection - adults. A urinary tract infection, or UTI, is an infection of the urinary tract. 1  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.
https://medlineplus.gov/ency/article/000521.htm
1 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.
http://www.medicinenet.com/urinary_tract_infection/page2.htm
what is uti
UTI is an infection of the urinary tract.   UTI is an infection of the urinary tract.