Strep Screen (Rapid)
Does this test have other names?
Throat swab, rapid strep test, rapid antigen test
What is this test?
The rapid strep screen is used to test for bacteria called group A streptococcus. Group A streptococcus bacteria cause illnesses such as strep throat and scarlet fever – a rash that may occur after a case of strep throat. Strep throat and scarlet fever can cause a number of symptoms, particularly a fever and a sore throat. These illnesses are quite contagious and require antibiotics to treat.
Doctors have two ways to test for group A streptococcus. For the rapid strep screen, your doctor or a nurse takes a sample of cells from your tonsils and back of the throat and tests it right in the doctor's office. You can get your results in as little as five minutes. If the rapid strep screen is positive, you have strep throat and no further tests may be needed.
Why do I need this test?
You may need this test if your doctor suspects that you have strep throat. Symptoms of strep throat can include:
Painful or difficult swallowing
Swelling or tenderness of the glands in the neck
Nausea or vomiting
Skin rashStomach ache
HeadacheLack of appetite
Tonsils that are swollen and red
Patches of white on the tongue or throat
You may need this test to confirm you have a bacterial infection instead of a viral infection before a doctor will prescribe antibiotics. You may also need this test if the results of a throat culture, which can provide a more accurate diagnosis, are unavailable for a few days.
What other tests might I have along with this test?
If the rapid strep screen is negative, your doctor may do another test called throat culture to make sure that strep is not the cause of your sore throat and other symptoms. This test also requires taking a swab of cells from your tonsils or back of the throat. The sample is sent to a laboratory, where it is grown, or cultured, and tested for strep bacteria. The results are available in about two days. Your results will reveal whether you have group A streptococcus.
Your doctor may also order:
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
Your test results will show whether you have group A streptococcus bacteria in the cells or mucus of your throat. A normal (negative) result will not show any group A streptococcus bacteria. If the test is positive, that means bacteria have been found and you likely have strep throat.
How is this test done?
The rapid strep screen requires taking a swab of mucus or cells from the back of your throat. The doctor, nurse, or laboratory technician will gently swipe the back of your throat with a long cotton swab. A second sample may be taken at the same time to be used in a throat culture if the rapid strep screen is negative.
Does this test pose any risks?
This test poses no known risks.
What might affect my test results?
Nothing is likely to affect the results of your test, as only the presence of group A streptococcus bacteria should give you a positive result.
How do I get ready for this test?
You don't need to prepare for this test.
- Alteri, Rick, MD
- Haines, Cynthia, MD