Urinary tract infections are a serious health problem affecting
millions of people each year. Infections of the urinary tract
are common--only respiratory infections occur more often. In
1997, urinary tract infections (UTIs) accounted for about 8.3
million doctor visits. Women are especially prone to UTIs for
reasons that are poorly understood. One woman in five develops a
UTI during her lifetime. UTIs in men are not so common, but they
can be very serious when they 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
liquid waste 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 triangle-shaped chamber in the lower abdomen. Urine
is stored in the