A throat culture is a test to find a bacterial, fungal, or viral 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 is negative.

Examples of infections that may be found during a throat culture include:

• Candida albicans. This fungus causes thrush, an infection of the mouth and tongue and sometimes of the throat. See an illustration of thrush in the mouth.
• Neisseria meningitidis. This bacteria can cause meningitis.
• Group A streptococcus. This bacteria can cause strep throat, 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 give false-negative results even when strep bacteria are present. When the results of a rapid strep test are negative, many health professionals recommend doing a throat culture to make sure that strep throat is not present.

If an infection grows in the culture, other tests may be done to check which antibiotic will treat the infection best. This is called susceptibility or sensitivity testing.

Why It Is Done

A throat culture may be done to:

• 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 health professional if you have recently taken any antibiotics.

How It Is Done

You will be asked to tilt your head back and open your mouth as wide as possible. Your health professional 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 sample.

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. This can prevent your child from moving around too much.