Pharyngitis

General Principles

Viruses are the most common cause of pharyngitis. GABHS pharyngitis is responsible for merely 5%–15% of cases in adults, with other bacteria responsible to a lesser extent. Unfortunately, 60% of adults with pharyngitis receive antibiotics.1

Diagnosis

Clinical Presentation

Fever, cervical lymphadenopathy, tonsillar exudates, and throat pain are the most common clinical manifestations. Distinguishing bacterial from viral pharyngitis on clinical grounds alone is difficult.

Differential Diagnosis

  • Acute HIV infection should be considered in the setting of pharyngitis with atypical lymphocytosis and negative Streptococcus and Epstein–Barr virus testing.
  • Epiglottitis should be considered in the febrile patient with severe throat pain, odynophagia, new-onset drooling, and dysphagia.
  • Suppurative complications including peritonsillar or retropharyngeal abscess should be considered in the patient with severe unilateral pain, muffled voice, trismus, and dysphagia.

Diagnostic Testing

  • Diagnostic testing is usually reserved for symptomatic patients with exposure to a case of streptococcal pharyngitis, those with signs of significant infection (fever, tonsillar exudates, and cervical adenopathy) or whose symptoms persist despite symptomatic therapy, and patients with a history of rheumatic fever.
  • Rapid antigen detection testing (RADT) is useful for diagnosing GABHS (>90% sensitivity and specificity), which requires antimicrobial therapy to prevent suppurative complications and rheumatic fever. A negative test does not reliably exclude GAS, making throat culture necessary if clinical suspicion is high.
  • Serology for Epstein–Barr virus (e.g., heterophile agglutinin or monospot) and examination of a peripheral blood smear for atypical lymphocytes should be performed when infectious mononucleosis is suspected.

Treatment

  • Most cases of pharyngitis are self-limited and do not require antimicrobial therapy.

Treatment for GABHS is indicated with a positive culture or RADT, if the patient is at high risk for development of rheumatic fever, or if the diagnosis is strongly suspected, pending culture results. Treatment options include penicillin V 500 mg PO q12h for 10 days, clindamycin 300 mg PO q8h for 10 days, azithromycin 500 mg PO on day 1 followed by 250 mg qday on days 2–5, or benzathine penicillin G 1.2 million units IM as a one-time dose.2 In some communities up to 15% of the GABHS isolates are resistant to macrolides.

  • Gonococcal pharyngitis is treated with ceftriaxone 250 mg IM as a single dose, plus azithromycin or doxycycline.

References

  1. Barnett ML, Linder JA. Antibiotic prescribing to adults with sore throat in the United States, 1997-2010. JAMA Intern Med. 2014;174(1):138-140.  [PMID:24091806]
  2. Shulman ST, Bisno AL, Clegg HW, et al. Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Clin Infect Dis. 2012;55(10):1279-1282.  [PMID:23091044]

Outline


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