Diagnosis

Your doctor will conduct a physical exam, look for signs and symptoms of strep throat, and probably order one or more of the following tests:

• Rapid antigen test. Your doctor may perform a rapid antigen test on a swab sample from your throat. This test can detect strep bacteria in minutes by looking for substances (antigens) in the throat. If the test is negative but your doctor still suspects strep, he or she might do a throat culture.
• Molecular (polymerase chain reaction, or PCR) test. This test is also done using a swab sample from your throat.
• Throat culture. A sterile swab is rubbed over the back of the throat and tonsils to get a sample of the secretions. It's not painful, but it may cause gagging. The sample is then cultured in a laboratory for the presence of bacteria, but results can take as long as two days.