Patients with group A beta-hemolytic streptococcal pharyngitis have classic symptoms of tonsillar swelling/exudates, tender anterior cervical lymphadenopathy, with no cough but with fever of >38ºC.
Clinical features suggestive of a viral etiology are conjunctivitis, absence of fever, coryza, cough, diarrhea, anterior stomatitis, hoarseness, discrete ulcerative lesions, rhinorrhea and viral exanthem and/or enanthem.
Antibiotics will not be needed for every patient that presents with sore throat but it should not be withheld if the clinical condition is severe or group A beta-hemolytic streptococcus is suspected.

Tonsillopharyngitis%20-%20acute Diagnosis


Conditions Where Lab Tests for Group A Beta-Hemolytic Streptococci are Not Available or Not Practical

  • Antibiotics will not be needed for every patient that presents with sore throat
  • Antibiotics should not be withheld if the clinical condition is severe or group A beta-hemolytic streptococci (GABS) is suspected
  • Modified Centor score can be used to decide on which patients need no testing, lab tests [throat swab or rapid antigen detection test (RADT)] or empiric antibiotic therapy
    • Score of 0 to 1 does not require testing or antibiotic therapy
    • Patients with score of 2 or 3 require testing, positive results warrant empiric therapy
    • Score of ≥4 is at high risk of GABS and empiric therapy is considered

Who Should be Tested for Group A Beta-Hemolytic Streptococci Pharyngitis?

  • Clinical presentation of group A beta-hemolytic streptococci and viral pharyngitis greatly overlap
  • Patients who have clinical and epidemiological findings suggestive of GABS pharyngitis should be tested for the presence of group A streptococci in the pharynx
  • Diagnostic testing of contacts of infected patients is not routinely recommended

FeverPAIN Score

  • May be used to assess the need to start antibiotic treatment as well as the severity of throat pain
  • High results may indicate streptococcal infection; results should be correlated with Centor criteria score

Centor Criteria

  • Used to assess the susceptibility of patients to GABS infection based on the patient’s age and symptoms
    • Results may assist in the decision to start antibiotic treatment
  • Uses a points system utilizing the following signs/symptoms:
    • Fever (>38°C/>100.4°F) (1)
    • Absence of cough (1)
    • Tender anterior cervical node (1)
    • Tonsillar exudate/swelling (1)
    • Age 3-14 years (1)
    • Age 15-44 years (0)
    • Age >44 years (-1)
  • Modified total risk based on total acute tonsillopharyngitis score:
  • Total Score Risk of GABS
     ≥4 51-53% 
     3 28-35% 
     2  11-17%
     1 5-10%
     ≤0  1-2.5%


Laboratory Tests

Throat Swab Culture

  • Gold standard for confirmation of clinical diagnosis of group A beta-hemolytic streptococci (GABS) pharyngitis
    • Recommended for those with history of contact with symptomatic persons with GABS pharyngitis, recurrent GABS infection and symptomatic patients at high risk for rheumatic fever
  • If done correctly, culture of a single throat swab on a blood agar plate has a sensitivity of 90-95%
  • Less expensive than rapid antigen detection test (RADT) and more readily available
  • Results take 24-48 hours
  • Does not differentiate between illness and carrier states
  • False-negative results may be seen in patients who have received antibiotic therapy shortly before or at the time the swab was obtained

Proper Technique of Obtaining a Throat Swab

  • Swab the surface of both the tonsils, tonsillar fossae and posterior pharyngeal wall
  • Do not include the mouth, uvula and oropharynx
  • Optimally done at onset of symptoms and before antimicrobial therapy is started

Rapid Antigen Detection Test (RADT)

  • Developed for the identification of GABS directly from throat swabs
  • More expensive than throat swab cultures, but results are available faster (within minutes)
  • With sensitivity of 80-90% and specificity of 90-99%
  • Does not differentiate between illness and carrier states
  • A rapid test can lead to earlier initiation of definitive therapy with the following advantages:
    • Reduced risk of spread of GABS
    • Reduced acute morbidity associated with illness
    • Earlier return of patient to work or school
  • A negative RADT result for an adult patient does not need to be confirmed with a throat culture because of the low incidence of streptococcal infection and low risk of rheumatic fever in this age group
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