Acute Pharyngitis

• Etiology: Respiratory viruses are the most common identifiable cause, although ∼30% of cases have no etiology identified.
  • Viruses: Rhinoviruses and coronaviruses cause ∼20% and ∼5% of cases, respectively; influenza and parainfluenza viruses are seasonal causes; HSV, coxsackievirus, CMV, EBV, and HIV are other important viral causes.
  • Bacteria:Group A Streptococcus (GAS) accounts for 5-15% of adult cases. Fusobacterium necrophorum, which can cause Lemierre disease, is increasingly identified as a cause of pharyngitis in adolescents and is isolated nearly as often as GAS. Rare bacterial causes that should be considered in appropriate exposure groups include Neisseria gonorrhoeae, Corynebacterium diphtheriae, Yersinia enterocolitica, and Treponema pallidum.
• Clinical manifestations: Specific signs and symptoms sometimes suggest that one etiology is more likely than another.
  • Respiratory viruses: Symptoms usually are not severe and are associated with coryza without fever, tender cervical lymphadenopathy, or pharyngeal exudates.
  • Influenza virus and adenovirus: evidenced by severe exudative pharyngitis with fever, myalgias, and-for adenovirus-conjunctivitis
  • HSV: presents as pharyngeal inflammation and exudates with vesicles and ulcers on the palate
  • Coxsackievirus (herpangina): characterized by small vesicles on the soft palate and uvula that rupture to form shallow white ulcers
  • EBV and CMV: present as acute pharyngitis in association with other signs of infectious mononucleosis (e.g., fever, fatigue, generalized lymphadenopathy)
  • HIV: associated with fever, acute pharyngitis, myalgias, malaise, and sometimes a maculopapular rash
  • Streptococci: Presentation ranges from mild disease to profound pharyngeal pain, fever, chills, abdominal pain, and a hyperemic pharyngeal membrane with tonsillar hypertrophy and exudates; coryzal symptoms are absent.
  • Other bacteria: often present as exudative pharyngitis without other specific findings
• Diagnosis: The primary goal of diagnostic testing is to identify cases of GAS pharyngitis.
  • Rapid antigen-detection tests for GAS offer good specificity (>90%) but variable sensitivity (65-90%); throat cultures are recommended for children, but not adults, in the setting of negative rapid testing.
  • Samples for specific cultures for other bacterial and viral causes should be obtained if these diagnoses are suspected.
  • If HIV is being considered, testing for HIV RNA should be performed.
• Treatment: Antibiotic treatment for GAS infection (penicillin VK, 500 mg PO tid × 10 days; or benzathine penicillin G, 1.2 million units IM × 1 dose) is recommended for pts with a positive rapid antigen detection test or throat swab culture; treatment modestly reduces symptom duration and prevents the development of rheumatic fever.
  • Long-term penicillin prophylaxis (benzathine penicillin G, 1.2 million units IM every 3-4 weeks; or penicillin VK, 250 mg PO bid) is indicated for pts at risk of recurrent rheumatic fever.
  • Symptom-based treatment of viral pharyngitis is generally sufficient.
  • Specific antiviral treatment (e.g., oseltamivir, acyclovir) may be helpful in selected cases of influenza and HSV infection.

Oral Infections

Oral-labial herpesvirus infections and oropharyngeal candidiasis are discussed in Chaps. 102 Infections with Herpes Simplex Virus, Varicella-Zoster Virus, Cytomegalovirus, Epstein-Barr Virus, and Human Herpesvirus Types 6, 7, and 8 and 108 Pneumocystis Pneumonia, Candidiasis, and Other Fungal Infections, respectively.