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 strep (streptococcal) bacteria are causing the sore throat.

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 health professional is able to collect enough secretions for an accurate test.

Results of a rapid strep test are available in 5 to 10 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, since 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.

Results

Findings of a rapid strep test may include the following.

Normal

A normal or negative test means that strep bacteria may not be present.

• Up to one-third of negative rapid strep test results are false. This means that in up to one-third of the cases when a rapid strep test is negative, the person actually has a strep throat infection.
• 62% to 95% of rapid strep tests done are accurate.
• A throat culture may be done if the rapid strep test result is negative.

Abnormal

An abnormal or positive strep test means that strep bacteria are present.

• In most cases, if the rapid strep test is positive, then 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).

What To Think About

The rapid strep test costs less than a throat culture and may diagnose strep throat quickly.

The rapid strep test is used when there is a need to rapidly identify strep throat to prevent the spread of strep or to treat children who have strep throat and who cannot return to day care or school until they have been treated for 24 hours.

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