Streptococcal pharyngitis

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  • Peak in 5-15yr old
  • Rare in <2yr of age
  • Accounts for only 15-30% of pharyngitis
  • Caused by S. pyogenes (Group A strep)
  • Peak season is late winter / early spring
  • Transmission is respiratory secretions
  • Incubation period is 24-72 hours
  • Antibiotics shorten symptoms by 16 hours

Clinical Features

culture positive strep pharyngitis with typical tonsillar exudate

Should NOT have a rash; if have scarlatiniform rash consider scarlet fever

Differential Diagnosis

Acute Sore Throat

Bacterial infections

Viral infections



Oral rashes and lesions


Modified Centor Criteria[3]

One point is given for each of the criteria:[3]

  1. Absence of a cough
  2. Swollen and tender cervical lymph nodes
  3. Temperature >38.0 °C (100.4 °F)
  4. Tonsillar exudate or swelling
  5. Age less than 15^
    • Subtract a point if age >44

^Testing is not needed in children <3 years old as both group A strep and rheumatic fever are rare, except if they have a sibling with the disease.[4]

Modified Centor score
Points Probability of Streptococcal pharyngitis Management
1 or fewer <10% No antibiotic or culture needed
2 11–17% Antibiotic based on rapid strep or culture
3 28–35%
4 or 5 52% Empiric antibiotics



Treatment can be delayed for up to 9 days and still prevent major sequelae

Penicillin Options:[5]

  • Penicillin V 250mg PO BID x 10d (child) or 500mg BID x 10d (adolescent)
  • Bicillin L-A 25-50K mg/kg IM x 1 (max dose = 1.2million)

Penicillin allergic (mild):[5]

  • Cefuroxime 10mg/kg PO QID x 10d (child) or 250mg PO BID x 4d

Penicillin allergic (anaphylaxis):[5]

  • Clindamycin 7.5mg/kg PO QID x 10d (child) or 450mg PO TID x 10d OR
  • Azithromycin 12mg/kg QD (child) or 500mg on day 1; then 250mg on days 2-5



  • Discharge


See Also


  1. Choby BA. Amer Fam Phys. 2009, 79(5), 383-90.
  2. Melio, Frantz, and Laurel Berge. “Upper Respiratory Tract Infection.” In Rosen’s Emergency Medicine., 8th ed. Vol. 1, n.d.
  3. 3.0 3.1 Choby BA (March 2009). "Diagnosis and treatment of streptococcal pharyngitis". Am Fam Physician 79 (5): 383–90. PMID 19275067.
  4. Shulman, ST; Bisno, AL; Clegg, HW; Gerber, MA; Kaplan, EL; Lee, G; Martin, JM; Van Beneden, C (Sep 9, 2012). "Clinical Practice Guideline for the Diagnosis and Management of Group A Streptococcal Pharyngitis: 2012 Update by the Infectious Diseases Society of America.". Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 55 (10): e86–102. doi:10.1093/cid/cis629. PMID 22965026.
  5. 5.0 5.1 5.2 ID society guidelines
  6. Hayward G, Thompson MJ, Perera R, Glasziou PP, Del Mar CB, Heneghan CJ. Corticosteroids as standalone or add-on treatment for sore throat. Cochrane Database Syst Rev. 2012 Oct 17;10:CD008268. PMID: 23076943.