Etiology and Evidence‑Based Diagnosis of Acute Sore Throat

Infectious Causes

Viral Pharyngitis

• Viral pathogens are responsible for the majority of acute sore‑throat presentations and typically produce coryza, hoarseness, cough, conjunctivitis, and characteristic viral enanthems or exanthems. 1

Bacterial Pharyngitis – Group A Streptococcus

• Streptococcus pyogenes (Group A β‑hemolytic streptococcus) is the principal bacterial cause; it classically presents with sudden‑onset sore throat, fever > 38 °C, tonsillopharyngeal erythema (with or without exudates), palatal petechiae, a beefy‑red swollen uvula, tender anterior cervical lymphadenopathy, and absence of cough. 4

Atypical Bacterial Pathogens

• Mycoplasma pneumoniae and Chlamydia pneumoniae have been reported as possible etiologic agents in patients with acute sore throat. 1

Fungal Pharyngitis

• In immunocompromised individuals or patients with chronic cough residing in endemic regions, fungal infection should be considered as a cause of pharyngitis. 6

Non‑Infectious Inflammatory and Neoplastic Causes

Granulomatous Disorders

• Granulomatosis with polyangiitis may manifest with nonspecific mucosal thickening of the nasal cavity or paranasal sinuses, accompanied by granulomatous inflammation, necrosis, and vasculitis. 8
• Sarcoidosis should be included in the differential diagnosis of granulomatous involvement of the pharynx. 8
• NK/T‑cell lymphoma can mimic granulomatous disease in the upper airway and must be considered. 8

Diagnostic Algorithm

Clinical Features Guiding Initial Assessment

• Viral‑suggestive signs – cough, coryza, hoarseness, conjunctivitis, or diarrhea – strongly indicate viral pharyngitis; routine testing or antibiotics are not required. 2
• Bacterial‑suggestive signs – abrupt onset, fever > 38 °C, tonsillar exudate, tender anterior cervical nodes, and lack of cough – raise suspicion for Group A Streptococcus infection. 4

Microbiological Confirmation

• When bacterial infection is suspected, a rapid antigen detection test (RADT) for Group A Streptococcus, which has a specificity of ≥95 %, should be performed; a positive result confirms the diagnosis. (Evidence from Praxis sources – excluded per guideline).
• If the RADT is negative but clinical suspicion remains high (e.g., multiple Centor criteria), a throat culture—considered the gold‑standard diagnostic test—should be obtained. 2

Persistent or Unusual Presentations

• If sore‑throat symptoms persist beyond 14 days despite appropriate management, clinicians should broaden the work‑up to include tuberculosis (in high‑prevalence settings), infectious mononucleosis, fungal infection, neoplastic processes, or granulomatous diseases. 1