Understanding Urinary Tract Infections - the Basics

What Are Urinary Tract Infections?

Urinary tract infection refers to an infection in the urinary bladder -- what doctors refer to as cystitis. Sometimes these spread to the upper tract in the kidney, which is called pyelonephritis. If the infection spreads to the prostate, then it is called prostatitis.

Acute cystitis is the sudden onset of a single episode of bladder infection; chronic cystitis is a recurring problem, with only fleeting infection-free periods. Simple, uncomplicated urinary tract infections are extremely common in women between the ages of 20 and 50, and are uncommon in young men. Children with UTIs may show different symptoms than adults.

People with a higher risk of developing urinary tract infections include:

• Those with conditions that affect the bladder's nerve supply (including diabetes, multiple sclerosis, and spinal cord injuries)
• Elderly men and women
• Pregnant women
• Women whose mothers had recurrent urinary tract infections
• People who have any kind of obstruction blocking the passage of urine (such as a tumor), kidney stone, or an enlarged prostate.
• Those who use a contraceptive diaphragm or spermicidal agents for contraception.
• People who use a catheter (a tube placed into the bladder to drain urine from the bladder into a bag outside of the body).
• Men who engage in anal intercourse, who have HIV infection, or who have never been circumcised.

Most of the above risk factors also increase the chance that a simple bladder infection may rapidly progress to a more serious kidney infection, or to sepsis (an infection which has entered the bloodstream and is affecting multiple organs throughout the body). Furthermore, pregnant women with kidney infections have a greater chance of delivering their babies prematurely, with all of the complications accompanying such prematurity.

What Causes Urinary Tract Infections?

Bacteria that are normally found in the gastrointestinal tract, such as Escherichia coli, cause most urinary tract infections. Other bacteria that can cause urinary tract infections include Staphylococcus saprophyticus, proteus, klebsiella and enterococcus.

In recent years, an increasing number of bladder infections in both men and women have been linked to two sexually transmitted organisms: Chlamydia trachomatis and mycoplasma.

Women are more prone to urinary tract infections because the tube running from the bladder to the outside (the urethra) is much shorter than in men. Because the urethral opening is relatively close to the anus in women, bacteria that are normal present from the colon can easily contaminate the female urethra. A urinary tract infection in young women is often associated with increased sexual activity.

In men, however, a bladder infection is almost always a symptom of an underlying disorder and a cause for concern. Often the infection has migrated from the prostate or some other part of the body, signaling problems in those locations. Or it may indicate a tumor or other obstruction is interfering with the urinary tract.

Chronic kidney infections in children are sometimes caused by a structural problem that allows urine to flow back from the bladder to kidneys (reflux), or by inability of the bladder to empty completely.