Strep A Test
Reviewed
Also called: Rapid strep test, Throat culture, Group A Streptococcus (GAS) throat culture, Streptococcus pyogenes test
Strep A tests check for strep A infections. A rapid strep test can provide results in 10-20 minutes.
Specimen: Throat swab from the back of the throat and tonsils
Why this test may be ordered
- Sudden and severe sore throat
- Pain or trouble swallowing
- Fever of 101 °F (38 °C) or more
- Swollen lymph nodes
- Red and swollen tonsils with white patches or pus streaks on tonsils or tiny red spots on the roof of the mouth (petechiae)
Preparation and collection
You don't need any special preparations for a rapid strep test or a throat culture.
If your provider thinks you might have strep throat, they will swab your throat to test for strep throat. Both tests are done in the same way. It's important to do a throat culture in children and teens since they can get rheumatic fever from an untreated strep throat infection.
There is no risk to having swab tests, but they may cause slight discomfort and/or gagging.
Understanding results
A rapid strep test quickly shows if group A strep bacteria are causing the illness. But a throat culture takes time to see if group A strep bacteria grow from the swab.
- Rapid test positive: If the rapid test is positive, it means you or your child has strep throat or another strep A infection. No further testing will be needed. Limitation: Someone who tests positive for strep throat but has no symptoms (called a "carrier") usually does not need antibiotics. Next step: If you or your child is diagnosed with strep throat, you will need to take antibiotics.
- Rapid test negative, strep still suspected: If the rapid test is negative but the provider thinks you or your child might have strep throat, they may order a throat culture. Limitation: Although it takes more time, a throat culture sometimes finds infections that the rapid strep test misses. Next step: If you or your child has not already provided a sample, you will get another swab test.
- Throat culture positive: If the throat culture is positive, it means you or your child has strep throat or other strep infection. Limitation: Having strep throat does not protect someone from getting it again in the future. Next step: It's important to take the antibiotics as prescribed and to finish the medicine even if you start feeling better.
- Throat culture negative: If the throat culture is negative, it means your symptoms are not being caused by strep A bacteria. Limitation: To find out what type of illness you have, your provider will first ask about your symptoms and do a physical exam. Next step: Your provider will probably order more tests to help make a diagnosis.
- A rapid strep test can sometimes miss an infection that a throat culture would find.
- Some people carry group A strep without symptoms (carriers) and usually do not need antibiotics.
- Having strep throat does not protect you from getting it again in the future.
What to do next
If you or your child is diagnosed with strep throat, you will need to take antibiotics. It's important to take the antibiotics as prescribed and to finish the medicine even if you start feeling better. People with strep throat should stay home from work, school, or daycare until they no longer have a fever and have taken antibiotics for at least 12-24 hours.
- What do my specific results mean?
- Do I need a throat culture if my rapid test was negative?
- How long should I stay home from work/school?
- What should I do if symptoms worsen or do not improve after starting antibiotics?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.