Urinary tract infection (UTI) is a bacterial infection that occurs anywhere along the urinary tract, which includes the kidneys, bladder, ureters (tubes that transfer urine from the kidneys to the bladder) and urethra (tube that empties the bladder during urination).

UTIs occur when bacteria, most commonly Escherichia coli (E. coli) or staphylococcus saprophyticus, enter the urethra and begin to multiply in the urinary tract. The body normally flushes bacteria out of the tract through urination. Both the lining of the bladder and urine have antibacterial properties as well, which makes it difficult for bacteria to grow. However, if too much bacteria is introduced into the urinary tract, it overwhelms the body’s natural germ-fighting capabilities and infection sets in. Certain individuals with weakened immune systems (e.g., patients with diabetes, elderly people) have a decreased ability to clear bacteria from the urinary tract.

Bacteria may gain access to the urethra in a number of ways, such as during sexual intercourse. It may also occur when wiping from the anus toward the vagina after a bowel movement or when changing a baby’s diapers. The use of catheters or tubes in the urethra can also introduce bacteria into the area.

UTIs account for almost 10 million doctor visits every year, according to the National Kidney Foundation. UTIs may occur in both genders and all age groups, although they are more common in women and older adults. Certain factors are associated with a greater risk of developing UTIs. A family history of UTIs, menopause, certain birth control methods, infrequent urination, urinary obstruction or structural abnormalities may all increase the risk of infection.

The most common symptoms of UTI include dysuria (a sensation of pain or burning during urination) and intense or frequent urges to urinate, even when an individual has little urine to pass. In infants and young children, common signs of UTI are irritability and poor feeding, although sometimes fever may be the only sign. In elderly people, symptoms may include mental confusion and incontinence.

Patients who suspect a UTI should consult their physician for proper diagnosis and treatment. A physician will likely compile a medical history and perform a physical examination. A urinalysis may be required to identify whether infection is present. In most cases, this is all that is required for a UTI diagnosis. In cases of recurrent UTIs, additional tests may be required.

UTIs are generally treated with antibiotics. Left untreated, infection can spread to the kidneys and bloodstream, resulting in serious health problems.  Hospitalization may be required in severe cases where infection has spread to the kidneys.