A throat culture is a test to check for a bacterial or 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 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.
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 doctors recommend doing a throat culture to make sure that strep throat is not present.
Neisseria meningitidis. This bacteria can cause meningitis.
If bacteria 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.
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 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.