Test Overview
A urine culture is a test to find and
identify germs (usually bacteria) that may be causing a
urinary tract infection (UTI). Urine in the bladder
normally is sterile—it does not contain any bacteria or other organisms (such
as
fungi). But bacteria can enter
the
urethra during urination.
A urine sample is kept under conditions that allow bacteria and
other organisms to grow. If few organisms grow, the test is negative. If
organisms grow in numbers large enough to indicate an infection, the culture is
positive. The type of organisms causing the infection are identified with a
microscope or by chemical tests.
Urinary tract infections are more common in women and girls than in
men. This may be partly because the female urethra is shorter and closer to the
anus, which allows bacteria from the intestines to
come into contact more easily with the urethra. (See an illustration of the
female
urinary tract
.) Men also have an antibacterial substance in their
prostate gland that reduces their risk.
If the urine culture is positive, other tests may be done to
help choose which antibiotic will do the best
job treating the infection. This is called
sensitivity testing.