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
fungi). But bacteria can enter the
urethra and cause an infection.
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.
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 a picture 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
Why It Is Done
A urine culture may be done to:
- Find the cause of a urinary tract infection
- Make decisions about the best treatment for a UTI. This is
called sensitivity testing.
- Find out whether treatment for a UTI
How To Prepare
You do not need to do anything before
you have this test. If you are taking or have recently taken
antibiotics, tell your doctor.
need to collect a urine sample. Avoid urinating just before having this
Talk to your doctor about any concerns you have regarding
the need for the test, its risks, how it will be done, or what the results will
mean. To help you understand the importance of this test, fill out the
medical test information form(What is a PDF document?).
How It Is Done
You will be asked to collect a
clean-catch midstream urine sample for testing. The first urine of the day is
preferred because bacterial levels will be higher.
Clean-catch midstream urine collection
helps protect the urine sample from germs that are normally found on the penis
- Wash your hands before collecting the
- If the collection container has a lid, remove it carefully
and set it down with the inner surface up.
- Clean the area around
your penis or vagina.
- A man should retract the foreskin, if
present, and clean the head of his penis thoroughly with medicated towelettes
- A woman should spread open the folds of skin around her
vagina with one hand, then use her other hand to clean the area around her
vagina and urethra thoroughly with medicated towelettes or swabs. She should
wipe the area from front to back to avoid spreading bacteria to the vagina that
is normally found around the anus.
- Begin urinating into the toilet or urinal. A
woman should continue holding apart the folds of skin around the vagina while
she is urinating.
- After the urine has flowed for several seconds,
place the collection container in the stream and collect about
60 mL (2 fl oz) of this
"midstream" urine without stopping the flow.
- Do not touch the rim
of the container to your genital area.
- Do not get toilet paper,
hair, feces, or menstrual blood in the urine sample.
urinating into the toilet or urinal.
- Carefully replace the lid on
the container. Wash your hands. Return the urine sample to the lab. If you are
collecting the urine at home and cannot get it to the lab within an hour,
refrigerate the sample. It can be refrigerated for up to 24 hours. Follow the
instructions from your lab.