Pharyngitis in Adults

Pharyngitis in Adults

Introduction

  • Acute pharyngitis is a common condition in outpatient settings.
  • Most cases are viral and self-limited.
  • Differentiating between viral, bacterial, and other serious causes is crucial.

Epidemiology

  • Approximately 12 million ambulatory care visits annually in the United States are due to pharyngitis.
  • This represents 1–2% of all outpatient visits.
  • Incidence peaks during childhood and adolescence (≈50% of cases before age 18).
  • In adults, pharyngitis is most common before age 40, with declining frequency thereafter.

Etiology

  • Infectious Causes:
    • Respiratory Viruses (25–45%):
      • Examples: adenovirus, rhinovirus, coronaviruses (including SARS-CoV-2), influenza, and parainfluenza.
    • Bacterial Causes:
      • Group A Streptococcus (GAS): Most common bacterial cause (5–15% in adults).
      • Other Bacteria:
        • Group C and G Streptococcus
        • Arcanobacterium haemolyticum (often in adolescents/young adults)
        • Fusobacterium necrophorum (noted in recurrent cases and Lemierre syndrome)
      • Atypical bacteria: Mycoplasma pneumoniae, Chlamydia pneumoniae
    • Other Pathogens and STIs:
      • Corynebacterium diphtheriae, Francisella tularensis
      • Sexually transmitted infections (e.g., acute HIV infection, gonococcal pharyngitis, syphilis).

Clinical Features

  • Common Symptoms:
    • Sore throat that worsens with swallowing.
    • Cervical lymphadenopathy (often tender, anterior nodes).
    • Associated symptoms: fever, headache, fatigue, and sometimes malaise.
  • Distinguishing Features:
    • Viral Pharyngitis:
      • Often comes with cough, nasal congestion, conjunctivitis, and sometimes a viral exanthem.
    • GAS Pharyngitis:
      • Sudden-onset sore throat, high fever, tonsillar exudates, palatal petechiae, and a scarlatiniform rash.

Centor Criteria

  • The Centor criteria are used to determine the likelihood of GAS in adults.
  • One point is given for each criterion:
    • Tonsillar exudates
    • Tender anterior cervical lymphadenopathy
    • Fever
    • Absence of cough
  • We generally test for GAS in patients with ≥3 Centor criteria.
  • Patients with Centor criteria <3 are unlikely to have GAS pharyngitis and generally do not need GAS testing.
  • The Centor criteria have relatively low sensitivity for the diagnosis of streptococcal pharyngitis.
  • Use of these criteria does not replace testing for GAS and should not be used to determine the need for antibiotic therapy.

Serious Conditions & Red Flags

  • Potentially Life-Threatening Conditions:
    • Airway obstruction due to severe pharyngeal inflammation.
    • Deep neck space infections such as peritonsillar abscess, parapharyngeal or retropharyngeal infections, and Lemierre syndrome.
  • Red Flags (Symptoms of Urgent Concern):
    • Muffled or "hot potato" voice.
    • Hoarseness, drooling, or pooling of saliva.
    • Stridor, respiratory distress, or abnormal positional breathing (“tripod” or “sniffing” position).
    • Bulging of the pharyngeal wall, trismus, or severe unilateral sore throat.

Evaluation Strategy

  • Systematic Approach:
    • First, rule out conditions needing urgent management (e.g., airway compromise).
    • Then, differentiate between viral and bacterial causes.
    • Use clinical judgment and standardized criteria (e.g., Centor criteria) to guide testing.
  • Initial Assessment:
    • Detailed history (onset, associated symptoms, exposure, and risk factors, including sexual history and recent exposures).
    • Physical examination focused on throat, tonsils, lymph nodes, and airway status.
  • Algorithm-Based Assessment:

Diagnostic Testing

  • Testing for Group A Streptococcus (GAS):
    • Indications:
      • Patients with clinical features (fever, tonsillar exudates, tender anterior cervical adenopathy) who lack viral symptoms.
      • Centor criteria: Testing usually recommended if ≥3 criteria are met.
    • Testing Methods:
      • Rapid Antigen Detection Test (RADT):
        • High specificity (88–99%), moderate sensitivity (77–92%).
      • Nucleic Acid Amplification Tests (NAAT):
        • Highly sensitive and specific; may be used as confirmatory testing.
    • Specimen Collection:
      • Adequate collection from both tonsillar fossae and the posterior pharynx is essential.
  • Additional Testing:
    • COVID-19 testing when indicated by local prevalence or patient exposure.
    • Screening for sexually transmitted infections in patients with risk factors (HIV, gonococcal pharyngitis, syphilis).

Management Principles

  • Viral Pharyngitis:
    • Supportive care is the cornerstone: rest, hydration, analgesics, humidification, and saline gargles.
  • Bacterial Pharyngitis (GAS):
    • Antibiotic treatment is recommended to shorten the illness duration and prevent complications (e.g., acute rheumatic fever).
  • Urgent Conditions:
    • Immediate referral/hospitalization for patients exhibiting red flags or signs of deep neck space infection.

Follow-Up Considerations

  • Expected Clinical Courses:
    • Viral Pharyngitis:
      • Most patients recover within 5–7 days with supportive care.
    • GAS Pharyngitis:
      • Improvement is usually evident within 24–72 hours once antibiotics are started.
  • Re-Evaluation:
    • Lack of improvement should prompt consideration of alternative diagnoses or complications (e.g., suppurative complications, mononucleosis, or even noninfectious causes).

Viral vs. Streptococcal Pharyngitis

  • Viral Pharyngitis:
    • Coryza (nasal and lacrimal edema and congestion).
    • Pharyngeal erythema.
    • Tonsillar edema.
  • Streptococcal Pharyngitis:
    • Tender, swollen anterior cervical lymph nodes (unilateral or bilateral).
    • Patchy tonsillar exudates.

Features Suggestive of Viral vs. Streptococcal Pharyngitis

  • Viral Pharyngitis:
    • Subacute onset of sore throat
    • Associated upper respiratory infection symptoms (cough, congestion, conjunctivitis, hoarse voice)
    • Pharyngeal erythema and tonsillar edema
    • Low-grade or absent fever
    • Other Findings (variably present):
      • Pharyngeal/tonsillar exudates
      • Oral ulcers
      • Viral exanthem
  • Streptococcal Pharyngitis:
    • Acute onset of sore throat
    • Absence of other upper respiratory infection symptoms
    • Pharyngeal erythema and tonsillar edema
    • Fever
    • Tonsillar exudates
    • Other Findings (variably present):
      • Known group A Streptococcus exposure
      • Palatal petechiae
      • Scarlatiniform rash
      • "Strawberry" tongue

Key Concepts

  • No single clinical feature distinguishes viral pharyngitis from streptococcal pharyngitis.
  • Combination suggestive of streptococcal pharyngitis:
    • Acute onset pharyngitis with tonsillar exudates
    • Fever
    • Cervical lymphadenopathy
    • Absence of other upper respiratory infection symptoms (e.g., cough)
  • Distinguishing is important because management strategies differ.
  • Symptomatic care alone is appropriate for viral pharyngitis.
  • Confirmed streptococcal pharyngitis requires antibiotic treatment.
  • Confirmatory testing for GAS (RADT, throat culture, or molecular assay) is indicated for all patients with suspected streptococcal pharyngitis.
  • When there is uncertainty, a clinical prediction rule such as the Centor score can help determine whether testing for GAS is warranted.

Evaluation Algorithm

  • Assess for signs/symptoms of severe infection:
    • Muffled voice
    • Drooling
    • Stridor
    • Respiratory distress
    • "Sniffing" or "tripod" position
    • Fever and rigors
    • Severe unilateral sore throat
    • Bulging of the pharyngeal wall/floor or soft palate
    • Trismus
    • Crepitus
    • Stiff neck
    • History of penetrating trauma to oropharynx
  • If present, stabilize and/or refer to emergency or inpatient setting.
  • Test for COVID-19 based on local prevalence or patient exposure.
  • If strong suspicion for other viral URI (cough, coryza, conjunctivitis, rhinorrhea, hoarseness, viral exanthem, or oral ulcers), offer supportive care.
  • If suspicion for GAS based on clinical features (fever > 100.4°F100.4°F/38°C38°C, sudden onset sore throat, tonsillopharyngeal or uvular edema, patchy exudates, tender lymphadenitis, scarlatiniform rash, history of GAS exposure):
    • If Centor criteria ≥3, perform RADT or NAAT.
    • If positive, treat with antibiotics.
    • If negative:
      • Residence in area with high GAS prevalence (e.g., college dormitory)
      • History of ARF
      • Immunosuppression
      • Close contact with a person with a history of ARF or immunosuppressed person
        • Throat culture or NAAT. If positive, treat. If negative, offer supportive care.
  • If uncertain, consider other causes (respiratory viruses, acute HIV, gonorrhea, noninfectious causes).