Strep Throat Test

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KEY POINTS

• A strep test is done to find out if group A strep bacteria are causing a sore throat.
• An untreated group A strep infection increases the risk for serious problems, such as rheumatic fever and heart problems.
• Your healthcare provider gets a sample by rubbing a cotton swab against the back of the throat. Ask your healthcare provider when you will get the results of your test.

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What is a strep test?

A strep test looks for infection in the throat caused by bacteria called group A streptococcus.

Why is it done?

A strep test is done to find out if certain strep bacteria are causing a sore throat. If the test finds group A strep bacteria, your healthcare provider may prescribe antibiotics. Treatment with antibiotics may help you feel better sooner than if you do not have treatment. More importantly, it also lowers the chance of more serious problems that can be caused by group A strep, such as heart or kidney problems from rheumatic fever. Most other common causes of sore throat do not need treatment with antibiotics.

How do I prepare for this test?

Make sure your healthcare provider knows about any medicines, herbs, or supplements that you are taking. Tell your healthcare provider if you took antibiotics during the 3 days before the test because that can affect the test result. Don't stop any of your regular medicines without first consulting with your healthcare provider.

Talk to your healthcare provider if you have any questions about the test.

How is the test done?

The strep test may be done in 2 ways: a rapid strep test or a throat culture. For both tests your healthcare provider gets a sample by rubbing a cotton swab against the back of the throat. The sample is sent to a lab.

• If the rapid strep test is done, the lab looks for a substance made by group A strep bacteria in the throat sample. If the test finds this substance, the result is positive and it means that strep bacteria were in the sample. The result takes 10 to 20 minutes. Your healthcare provider may be able to do this test in his or her office.
• If a throat culture is done, the swab is sent to the lab and tested for growth of the bacteria or other germs. If you have an infection, it may take 2 to 3 days to get the results.

Ask your healthcare provider when and how you will get the result of the test.

What does the test result mean?

Usually, a positive strep test means that you have strep, and a negative result means that you do not have strep.

The rapid strep test is very accurate and reliable if it is positive. If it is negative, your provider may choose to send a throat culture to confirm that the result is accurate. If the culture is negative, it is likely that your sore throat was caused by a virus.

What if my test result is not normal?

Test results are only one part of a larger picture that takes into account your medical history, physical exam, and current health. Sometimes a test needs to be repeated to check the first result. Talk to your healthcare provider about your result and ask questions, such as:

• If you need more tests
• What kind of treatment you might need
• What other changes you might need to make