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Strep Test

Last updated Oct. 17, 2018

Approved by: Maulik P. Purohit MD, MPH

The Strep Test detects the presence of S. pyogenes in a throat swab sample. It is used to diagnose strep throat. It is also used to guide in administering suitable antibiotic therapy.

What are the other Names for this Test? (Equivalent Terms)

  • Direct Strep Screen Test
  • Group A Beta Hemolytic Streptococcus Test
  • Streptococcal Screen Test 

What is Strep Test? (Background Information)

  • A sore throat may be caused by a variety of factors. The bacterium Streptococcus pyogenes is one of the reasons for a sore throat. This bacterium causes the condition commonly referred to as “strep throat”
  • Strep throat is less common than other causes of a sore throat (at 5-20%) such as viruses. However, it may potentially cause fever and kidney damage if left untreated
  • Strep throat is contagious. It is spread from an infected individual through close contact such as coughing and sneezing. The infected droplet causes the infection. It can also be transmitted through kissing and sharing utensils. Children are especially susceptible to the condition
  • The Strep Test detects the presence of S. pyogenes in a throat swab sample. It is used to diagnose strep throat. It is also used to guide in administering suitable antibiotic therapy

What are the Clinical Indications for performing the Strep Test?

Following are the clinical indications for performing a Strep Test:

  • Sore throat
  • Chills
  • Headache
  • Fatigue
  • Gray-white patches on the tonsils
  • Swollen lymph nodes
  • Loss of appetite

How is the Specimen Collected for Strep Test?

Following is the specimen collection process for Strep Test:

Sample required: Throat swab

Process: Gently scraping the back of the throat with a sterile Q-tip shaped device.

Preparation required: No special preparation is needed prior to the test. 

What is the Significance of the Strep Test Result?

  • A positive result may indicate infection with Streptococcus pyogenes and strep throat. This may result in:
    • Rheumatic fever
    • Scarlet fever
    • Streptococcal glomerulonephritis                  
  • A negative result does not rule out infection with S. pyogenes, but may warrant further testing such as culture tests  

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results based on the overall clinical scenario. 

Additional and Relevant Useful Information:

  • The Strep Test is a ‘quick’ test; the results of which are usually reported back in an hour 

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

References and Information Sources used for the Article:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Nov. 12, 2014
Last updated: Oct. 17, 2018