Overview of Urinary Tract Infection
Urinary tract infections are among the most common of bacterial infections. They occur in people of all ages, women significantly more than men.

In the United States, an estimated eight to 10 million visits are made to the physician each year for the treatment of UTIs.

The urinary system consists of the kidneys, ureters, bladder, and urethra.

Urine is formed in the kidneys, waste-filtering organs located in the mid-back, just below the rib cage. Urine leaves the kidneys and flows down the ureters, two thin tubes that empty into the bladder, the hollow, muscular organ that holds urine. The urethra is the tube that transports urine out of the body from the bladder.

Causes of Urinary Tract Infection
Most UTIs arise from bacteria that normally live in the colon and rectum, and are present in bowel movements. These bacteria cling to the opening of the urethra, begin to multiply, and travel up to the bladder. The flow of urine from the bladder usually washe s bacteria out of the body.

However, because women have a shorter urethra than men, bacteria can reach the bladder more easily and settle in the bladder wall. Much less often, bacteria spread to the kidney from the bloodstream.

Types of Urinary Tract Infection
There are three types of urinary tract infection:

• Cystitis, the most common UTI, is an inflammation of the bladder. It almost always occurs in women. In most cases, the infection affects only the surface of the bladder and is brief and acute.
• Pyelonephritis, more commonly known as a kidney infection, usually occurs when a lower UTI spreads to the upper tract. Occasionally, bacteria will spread to the kidney from the bloodstream. Kidney infections are much less common, but often more serious than b ladder infections.
• Urethritis is an inflammation of the urethra. Men commonly contract urethritis through sexual intercourse with an infected partner. Urethritis may also result from trauma to the area or from a medical procedure involving a catheter, a tube inserted through th e urethra to the bladder to drain the urine.

Symptoms of Urinary Tract Infection
Symptoms may include a frequent urge to urinate, regardless of whether the bladder is full or empty, and pain and burning with urination. The urine itself may look milky or cloudy, or have a strong smell.

Women often feel an uncomfortable pressure in the pelvic area, and some men experience a feeling of fullness in the rectum. Fever may mean the infection has reached the kidneys.

Other symptoms of kidney infection include pain in the back or side below the ribs, nausea, or vomiting.