Throat Culture Throat swab culture is a laboratory test done to isolate and identify organisms that may cause infection in the throat. The back of the throat is swabbed with a sterile cotton swab near the tonsils. The swab is placed in a tube of culture medium. In order to improve the chances of detecting bacteria, the swab may be used to scrape the back of the throat several times. This test is used primarily to identify strep throat. However, depending on the type of culture medium used, other organisms may be detected. Your child's throat may be sore at the time the test is taken. He/she may experience a gagging sensation when the back of the throat is touched with the swab, but the test only lasts a few seconds.