The Strep Test is used to test for the presence of beta-hemolytic Group A streptococci in pharyngeal smears.
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The infection caused by these microorganisms (Streptococcus pyogenes) is usually easily treated with antibiotics. If left untreated, it can lead to complications such as rheumatic fever and post-streptococcal glomerulonephritis. Testing for Streptococcus is also helpful because it allows the doctor to avoid unnecessary antibiotic use for infections caused by viruses, thereby reducing antibiotic resistance.
The rapid Streptococcus test has a specificity and sensitivity of approximately 98% and 95%, respectively. It is performed using immunochemical methods involving monoclonal antibodies to antigens of group A Streptococcus and material from a throat swab as a sample. The test can only detect the presence of group A beta-hemolytic Streptococcus. Other causes of pharyngitis and tonsillitis cannot be detected with this test.
Diagnosis of group A beta-hemolytic streptococcal pharyngitis should be made based on laboratory tests and not clinically. The rapid Strep Test is helpful but is not sensitive enough to be used alone. The rapid Strep Test, followed by throat swab culture and sensitivity testing, has the highest positive predictive value.
If the test is positive, the patient should be started on an antibiotic, such as penicillin or erythromycin, for a penicillin allergy. If the test is negative, culture and sensitivity testing should be performed to determine whether the rapid Strep test was a false negative.
A positive result does not distinguish between people with active streptococcal infection and those with streptococci carriers.
Possible Interpretations of Pathological Values
- Positive: B-hemolytic Streptococcus infection of group A.
- Negative: Absence of infection, viral infection, false negative result
Important Note
Laboratory test results are the most critical parameter for diagnosing and monitoring all pathological conditions. Between 70 to 80% of diagnostic decisions are based on laboratory tests. Correctly interpreting laboratory results allows a doctor to distinguish "healthy" from "diseased."
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be analyzed based on each case and family history, clinical findings, and the results of other laboratory tests and information. Your physician should explain the importance of your test results.
At Diagnostiki Athinon, we answer any questions you may have about the test you perform in our laboratory and contact your doctor to ensure you receive the best possible medical care.
