For a rapid strep test, the throat and tonsils are swabbed to collect bacteria from the infected area for testing. The bacteria are analyzed to see whether Group A strep (streptococcal) bacteria are causing the sore throat. The rapid strep test is not used in many parts of Canada.
A good sample of throat secretions is needed to make sure the test is accurate. A person must remain very still during the procedure so that the doctor is able to collect enough secretions for an accurate test.
Results of a rapid strep test are available in 10 to 15 minutes.
Why It Is Done
A rapid strep test may be done in the following cases:
- A person has symptoms of strep throat infection.
- A person has been exposed to strep during an epidemic of rheumatic fever.
- The person has a personal or family history of rheumatic fever or other serious infections (such as toxic shock syndrome) and has been exposed to strep. In these cases, if there are no symptoms, a culture may be done first because it is more accurate than a rapid strep test.
In general, it is not necessary to test people who have been exposed to strep throat but do not have any symptoms.
Findings of a rapid strep test may include the following.
A normal or negative test means that strep bacteria may not be present.
- Sometimes, negative results are wrong. This means that you may have a negative rapid strep test result and still have strep throat.
- A throat culture may be done if the rapid strep test result is negative.
An abnormal or positive strep test means that strep bacteria are present.
- Antibiotic treatment can be started.
- A positive test result does not distinguish those people with an active strep infection from those who are carriers of strep bacteria but actually have a viral infection (rather than a bacterial one).