Strep A Test
Reviewed
Also called: Rapid strep test, Throat culture, Group A Streptococcus (GAS) throat culture, Streptococcus pyogenes test
A strep A test checks for group A Streptococcus bacteria, which cause strep throat and other infections. There are two types: a rapid strep test (results in 10–20 minutes) and a throat culture (results in 24–48 hours). The test helps determine if a sore throat is due to strep (bacterial) or a viral infection, guiding appropriate treatment with antibiotics to prevent complications like rheumatic fever.
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
No special preparations needed.
You will tilt your head back and open your mouth wide. The provider uses a tongue depressor to hold down your tongue and a special swab to take a sample from the back of your throat and tonsils. The sample may be tested in the office or sent to a lab.
There is no risk to having swab tests, but they may cause slight discomfort and/or gagging.
Understanding results
Your healthcare provider will interpret your results. The following patterns are based on the test type used.
- Rapid test positive: You or your child has strep throat or another strep A infection. No further testing is needed. Limitation: False positives are rare but possible. Discuss with your provider. Next step: Antibiotics are typically prescribed. Take all medicine as directed, usually for 10 days. Stay home from work, school, or daycare until no fever and after at least 12–24 hours of antibiotics.
- Rapid test negative, throat culture positive: You or your child has strep throat or another strep A infection. Limitation: The rapid test may miss some infections; the culture is more accurate. Next step: Antibiotics are typically prescribed. Take all medicine as directed, usually for 10 days. Stay home from work, school, or daycare until no fever and after at least 12–24 hours of antibiotics.
- Throat culture negative: Your symptoms are not caused by strep A bacteria. Limitation: A negative culture does not rule out other infections. Next step: Your provider will likely order more tests to find the cause of your symptoms.
- 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 diagnosed with strep throat, take antibiotics as prescribed for the full course (usually 10 days). Stay home until fever-free and after at least 12–24 hours of antibiotics. Wash hands often, cover coughs and sneezes, and clean frequently touched surfaces to prevent spread.
- 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?