health

A urinary (YOOR-ih-nair-e) tract infection, or UTI, is an infection that
occurs in any part of the urinary tract. The urinary tract is made up of the
urethra*, bladder*, ureters*, and kidneys*.
A UTI usually is caused by bacteria that under normal circumstances
should never be present in the urine. The bacterium most often responsible
for UTIs is Escherichia coli (eh-sher-IH-she-ah KOH-lye). Many
kinds of E. coli bacteria normally are found in human intestines*, but
sometimes they are able to make their way into the urethra. When this
happens, the bacteria can spread up into other parts of the urinary tract
and cause an infection. Other types of bacteria from the intestines and
some viruses also can produce infections in the urinary tract. The bacteria
Chlamydia (kla-MIH-dee-uh) and Mycoplasma (my-ko-PLAZ-muh) can
cause UTIs as well, but these types of infections usually stay in the urethra
or reproductive system.
The type of UTI that a person contracts depends on which part of the
urinary system is infected with bacteria. If bacteria grow in the urethra
and cause inflammation, the condition is called urethritis (yoo-ree-THRYtis).
If the infection involves the bladder, the condition is called cystitis
(sis-TIE-tis). If infection has spread to the kidneys, the condition is called
pyelonephritis (py-uh-lo-nih-FRY-tis).