Discusses test used to find cause of a sore throat. Covers conditions caused by fungal or bacterial infection. Covers how test is done. Looks at what results might mean. Links to info on rapid strep test, throat culture, and sensitivity testing.
A throat culture is a
test to check for a
fungal infection in the throat. A sample swabbed from
the throat is put in a special cup (culture) that allows infections to grow. If
an infection grows, the culture is positive. The type of infection is found
using a microscope, chemical tests, or both. If no infection grows, the culture
Examples of infections that may be found during a
throat culture include:
Candida albicans. This
thrush, an infection of the mouth and tongue and
sometimes of the throat.
Group A streptococcus. This bacteria can cause
scarlet fever, and
rheumatic fever. If strep throat is likely, a test
called a rapid strep test (or quick strep) may be done before a throat culture.
With a rapid strep test, results are ready in 10 minutes instead of 1 to 2 days
with a throat culture. If the rapid strep test results are positive,
antibiotics can be started immediately. A throat
culture is more accurate than the rapid strep test. The rapid strep test can
false-negative results even when strep bacteria are
present. When the results of a rapid strep test are negative, many doctors recommend doing a throat culture to make sure that strep throat
is not present.
Neisseria meningitidis. This bacteria can cause
If bacteria grows in the culture, other tests may be
done to check which antibiotic will treat the infection best. This is called
Most sore throats are caused by an infection with a virus, such as a cold or flu. Throat cultures are not done for viral infections because it is very hard to grow viruses and it is expensive.
Why It Is Done
A throat culture may be done
Find the cause of a sore throat. Most sore
throat infections are caused by a virus. A throat culture shows the difference
between a bacterial infection and a viral infection. Finding the organism that
is causing the infection can guide treatment.
Check a person who
may not have any symptoms of infection but who carries bacteria that can spread
to others. This person is called a carrier.
How To Prepare
You do not need to do anything before
you have this test. Tell your doctor if you have recently taken
How It Is Done
You will be asked to tilt your head
back and open your mouth as wide as possible. Your doctor will
press your tongue down with a flat stick (tongue depressor) and then examine
your mouth and throat. A clean swab will be rubbed over the back of your
throat, around your tonsils, and over any red areas or sores to collect a
The sample may also be collected using a throat washout.
For this test, you will gargle a small amount of salt water and then spit the
fluid into a clean cup. This method gives a larger sample than a throat swab
and may make the culture more reliable.
If your child needs a
throat culture, you may hold your child on your lap while the sample is taken. This can prevent your
child from moving around too much.
How It Feels
You may feel like gagging when the swab
touches the back of your throat. If your throat is sore, the swabbing may be
Generally there is no chance of problems with
collecting a sample for a throat culture. Your doctor can talk to
you about any specific risks of the test.
A throat culture is a test to find a
fungal infection in the throat. Throat culture test
results for bacterial infections are ready in 1 to 2 days, depending on which
bacteria are being tested for. Test results for a fungus may take about 7
Rapid strep test results are ready in 10 to 15 minutes. This
test is only for bacterial infections caused by strep bacteria.
Rapid strep test
Normal (negative results):
No strep bacteria are detected. A throat culture may be
Abnormal (positive results):
Strep bacteria are detected. This means you have
strep throat. Antibiotics can be started
No infection (bacteria or fungi) grows in
A negative throat culture may mean that the
cause of your infection is a
virus, rather than bacteria or fungus.
Some viruses that cause throat infections include:
Fungus grows in the culture. The most
common fungal throat infection is
thrush, caused by the fungus Candida albicans.
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
antibiotics recently. This may prevent the growth of
an infection in the culture.
Contamination of the throat culture
sample by other types of bacteria from the mouth.
mouthwashes before the culture is taken.
What To Think About
If you need to be tested for strep throat, the
choice between a rapid strep test and a throat culture may not be clear. Talk
to your doctor about the rapid strep test versus a throat culture.
A culture that does not grow any bacteria or fungus
generally means that you either have a viral infection or that an infection is
not present. Other things, such as the amount of sample, the timing of the
sample, the type of culture done, and recent use of antibiotics, can prevent the
growth of bacteria or fungus in the culture.
may be done to help choose the antibiotic that will best treat the bacteria
causing an infection.
Some people carry bacteria but do not have
symptoms of an infection. A throat culture is generally done only if the
person's medical history and physical examination suggest that an infection is
Other Works Consulted
American Academy of Pediatrics (2009). Group A
streptococcal infections. In LK Pickering et al., eds., Red Book: 2009 Report of the Committee on Infectious Diseases, 28th ed., pp.
616–628. Elk Grove Village, IL: American Academy of Pediatrics.
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
How this information was developed to help you make better health decisions.