Urinary Tract Infection in Adults
(UTI in Adults)
Urinary tract infection introduction
Urinary tract infections are a serious health problem affecting millions of
people each year.
Infections of the urinary tract are the second most common type of infection
in the body. Urinary tract infections (UTIs) account for about 8.3 million
doctor visits each year. Women are especially prone to UTIs for reasons that
are not yet well understood. One woman in five develops a UTI during her
lifetime. UTIs in men are not as common as in women but can be very serious when
they do occur.
The urinary system consists of the kidneys, ureters, bladder, and urethra.
The key elements in the system are the kidneys, a pair of purplish-brown organs
located below the ribs toward the middle of the back. The kidneys remove excess
liquid and wastes from the blood in the form of urine, keep a stable balance of
salts and other substances in the blood, and produce a hormone that aids the
formation of red blood cells. Narrow tubes called ureters carry urine from the
kidneys to the bladder, a sack-like organ in the lower abdomen. Urine is stored
in the bladder and emptied through the urethra.
The average adult passes about a quart and a half of urine each day. The
amount of urine varies, depending on the fluids and foods a person consumes. The
volume formed at night is about half that formed in the daytime.
What are the causes of UTI?
Normally, urine is sterile. It is usually free of bacteria, viruses, and
fungi but does contain fluids, salts, and waste products. An infection
occurs when tiny organisms, usually bacteria from the digestive tract, cling
to the opening of the urethra and begin to multiply. The urethra is the tube
that carries urine from the bladder to outside the body. Most infections
arise from one type of bacteria, Escherichia coli (E. coli), which normally
lives in the colon.
In many cases, bacteria first travel to the urethra. When bacteria multiply,
an infection can occur. An infection limited to the urethra is called urethritis.
If bacteria move to the bladder and multiply, a bladder infection, called
cystitis, results. If the infection is not treated promptly, bacteria may then
travel further up the ureters to multiply and infect the kidneys. A kidney
infection is called pyelonephritis.
Microorganisms called Chlamydia and Mycoplasma may also cause UTIs in both
men and women, but these infections tend to remain limited to the urethra and
reproductive system. Unlike E. coli, Chlamydia and Mycoplasma may be sexually
transmitted, and infections require treatment of both partners.
The urinary system is structured in a way that helps ward off infection. The
ureters and bladder normally prevent urine from backing up toward the kidneys,
and the flow of urine from the bladder helps wash bacteria out of the body. In
men, the prostate gland produces secretions that slow bacterial growth. In both
sexes, immune defenses also prevent infection. But despite these safeguards,
infections still occur.
|Picture of the urinary tract