Urinary tract infection

A urinary tract infection is an infection that begins in your urinary system. Your urinary system is composed of the kidneys, ureters, bladder and urethra. Any part of your urinary system can become infected, but most infections involve the lower urinary tract — the urethra and the bladder.

Women are at greater risk of developing a urinary tract infection than are men. A urinary tract infection limited to your bladder can be painful and annoying. However, serious consequences can occur if a urinary tract infection spreads to your kidneys.

Antibiotics are the typical treatment for a urinary tract infection. But you can take steps to reduce your chance of getting a urinary tract infection in the first place.

Symptoms

Not everyone with a urinary tract infection develops recognizable signs and symptoms, but most people have some.

In general, urinary tract infection signs and symptoms develop rapidly and can include:

    * A strong, persistent urge to urinate
    * A burning sensation when urinating
    * Passing frequent, small amounts of urine
    * Blood in the urine (hematuria) or cloudy, strong-smelling urine
    * Bacteria in the urine (bacteriuria)
The urinary system is composed of the kidneys, ureters, bladder and urethra. All play a role in removing waste from your body. Urinary tract infections typically occur when bacteria enter the urinary tract through the urethra and begin to multiply in the bladder. Although the urinary system is designed to keep out such microscopic invaders, the defenses sometimes fail. When that happens, bacteria may take hold and multiply into a full-blown infection in the urinary tract.

The most common urinary tract infections occur mainly in women and affect the bladder and urethra.

    * Infection of the bladder (cystitis) is usually caused by Escherichia coli (E. coli), a species of bacteria commonly found in the gastrointestinal tract. Sexual intercourse may lead to cystitis, but you don't have to be sexually active to develop it. All women are susceptible to cystitis because of their anatomy — specifically, the close proximity of the urethra to the anus and the short distance from the urethral opening to the bladder.
    * Infection of the urethra (urethritis) can occur when the gastrointestinal bacteria make the short trip from the anus to the urethra. In addition, because of the female urethra's proximity to the vagina, sexually transmitted diseases (STDs), such as herpes simplex virus, gonorrhea and chlamydia, also are possible causes of urethritis.
The urinary tract — an organ system that removes waste from the body — is composed of the kidneys, ureters, bladder and urethra. Although urinary tract infections occur more frequently in women, men can develop them, too.

Risk factors

Some people appear to be more likely than are others to develop urinary tract infections.

Risk factors include:

    * Being female. Half of all women will develop a urinary tract infection at some point during their lives, and many will experience more than one. A key reason is their anatomy. Women have a shorter urethra, which cuts down on the distance bacteria must travel to reach the bladder.
    * Being sexually active. Women who are sexually active tend to have more urinary tract infections. Sexual intercourse can irritate the urethra, allowing germs to more easily travel through the urethra into the bladder.
    * Using certain types of birth control. Women who use diaphragms for birth control also may be at higher risk, as are women who use spermicidal agents.
    * Aging. After menopause, urinary tract infections may become more common because tissues of the vagina, urethra and the base of the bladder become thinner and more fragile due to loss of estrogen.
    * Kidney stones or any other urinary obstruction.
    * Diabetes and other chronic illnesses that may impair the immune system.
    * Prolonged use of tubes (catheters) in the bladder.

Recurrent urinary tract infections
In women, the immune system may play a role in the risk of recurrent urinary tract infections. Bacteria can attach to cells in the urinary tract more easily in women lacking protective factors that normally allow the bladder to shed bacteria. More research is needed to determine the exact factors involved and how these factors can be manipulated to benefit women with frequent urinary tract infections.