1. Just a Sore Throat or Strep Slideshow
2. Take the Strep Throat Quiz!
3. Infectious Mononucleosis Slideshow

Medical Author:

Steven Doerr, MD

Steven Doerr, MD

Steven Doerr, MD, is a U.S. board-certified Emergency Medicine Physician. Dr. Doerr received his undergraduate degree in Spanish from the University of Colorado at Boulder. He graduated with his Medical Degree from the University Of Colorado Health Sciences Center in Denver, Colorado in 1998 and completed his residency training in Emergency Medicine from Denver Health Medical Center in Denver, Colorado in 2002, where he also served as Chief Resident.

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Medical Editor:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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The definitive diagnosis of strep throat can be made with simple laboratory testing. However, some health care practitioners may choose to make the diagnosis of strep throat clinically (without laboratory testing) if they feel that a person's signs and symptoms are highly suggestive of this illness. Though certain predictive factors may make strep throat more likely than a viral sore throat, it is important to note that there is not one clinical sign or symptom alone which definitively establishes the diagnosis of strep throat. Helpful predictive factors that make strep throat more likely include:

• age between 5 to 15 years,
  
  
• illness occurring between late fall and early spring,
  
  
• fever,
  
  
• redness and swelling of the throat with tonsillar exudates,
  
  
• enlarged and tender lymph nodes in the neck, and
  
  
• absence of symptoms suggestive of a viral infection, such as cough or runny nose.

The most commonly used laboratory tests for diagnosing strep throat include the following readily available tests:

Rapid antigen detection test: A rapid strep test can be done by health care practitioners by gently swabbing the back of the throat and tonsils. The results are generally available within several minutes in some clinics. If the result is positive for streptococcal bacteria, the diagnosis of strep throat is confirmed. However, a negative test result does not definitively rule out strep throat, as rapid strep tests are not always accurate (about 20% to 30% of rapid tests fail to detect streptococcal bacteria when they are present).

Throat culture: If the rapid test result is negative, generally a throat culture is sent to the lab for further testing. The throat culture is obtained in the same manner as the rapid strep test. The results are generally available within 24 to 48 hours. If streptococcal bacteria grow during this time, the test result is positive, and the diagnosis of strep throat is confirmed. The throat culture is the gold standard test for diagnosing strep throat.

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