Streptococcal pharyngitis

Background

Anatomy of the posterior pharynx.
  • Peak in 5-15yr old[1]
  • Rare in <2yr of age[1]
  • Accounts for only 15-30% of pharyngitis[1]
  • Caused by S. pyogenes (Group A strep)[1]
  • Peak season is late winter / early spring[1]
  • Transmission is respiratory secretions[1]
  • Incubation period is 24-72 hours[1]
  • Antibiotics shorten symptoms by 16 hours[1]

Clinical Features

culture positive strep pharyngitis with typical tonsillar exudate

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

Modified Centor Criteria[1]

One point is given for each of the criteria:[1]

  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
Modified Centor score
Points Probability of Streptococcal pharyngitis
1 or fewer <10%
2 11–17%
3 28–35%
4 or 5 52%

Differential Diagnosis

Acute Sore Throat

Bacterial infections

Viral infections

Noninfectious

Other

Oral rashes and lesions

Evaluation

  • Per a 2016 Cochrane Review of rapid strep tests in children, tests on average had a specificity of 95% and sensitivity of 86%, regardless of type of rapid strep test used (enzyme immunoassays or optical immunoassays).[3]

Rapid Antigen Detection Test Algorithm for Acute Pharyngitis[4]

Category Testing and Treatment
Clinical features strongly suggesting viral etiology (eg. cough, rhinorrhea, hoarseness, oral ulcers)
  • None
<3 years old
  • None because immature immune system not mature enough to develop anti-streptolysin O (ASO) antibodies and acute rheumatic fever[5].
    • Unless they have a special risk factor (e.g. older sibling with GAS infection)
CENTOR = 1
  • None
None of the above with CENTOR ≥2
  • Send rapid antigen detection test
    • Positive = treat
    • Negative
      • Children and adolescents
        • Send back up throat culture (treat later, if positive)
      • Adults
        • None (no need for back up throat culture)

Diagnostic testing or empiric treatment of asymptomatic household contacts of patients with acute streptococcal pharyngitis is not routinely recommended

Management

Antibiotics

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

Penicillin Options:[6]

  • Penicillin V 250mg PO BID x 10d (child) or 500mg BID x 10d (adolescent or adult)
  • Bicillin L-A <27 kg: 0.6 million units; ≥27 kg: 1.2 million units IM x 1
  • Amoxicillin 500-875 mg PO q12h or 250-500 PO q8h for 10d[7]

Penicillin allergic (mild):[6]

  • Cefuroxime 10mg/kg PO QID x 10d (child) or 250mg PO BID x 4d
  • Cefixime 400mg/day PO in single daily dose x10d or divided q12hr x10d

Penicillin allergic (anaphylaxis):[6]

  • 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

Steroids

Disposition

  • Discharge

Complications

See Also

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Choby BA (March 2009). "Diagnosis and treatment of streptococcal pharyngitis". Am Fam Physician 79 (5): 383–90. PMID 19275067.
  2. Melio, Frantz, and Laurel Berge. “Upper Respiratory Tract Infection.” In Rosen’s Emergency Medicine., 8th ed. Vol. 1, n.d.
  3. Cohen JF, Bertille N, Cohen R, Chalumeau M. What is the performance of rapid tests for the diagnosis of strep throat in children?. Cochrane Review. Published 4 July 2016. https://www.cochrane.org/CD010502/ARI_what-performance-rapid-tests-diagnosis-strep-throat-children
  4. Shulman, et al. 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 2012;55(10):1279–82
  5. David Cisewski An Understated Myth? Strep Throat & Rheumatic Fever
  6. 6.0 6.1 6.2 Shulman, et al. 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 2012;55(10):1279–82
  7. Shah, U. K., MD. (2020, October 14). Tonsillitis and Pharyngitis Organism-Specific Therapy: Specific Organisms and Therapeutic Regimens. Emedicine. https://emedicine.medscape.com/article/2011872-overview
  8. EBQ:TOAST Trial