sore throat
Summary
Sore throat (pharyngitis) is inflammation of the pharynx, most commonly caused by viral infection, though group A Streptococcus (GAS) is the key bacterial cause to identify due to risk of complications. Clinical evaluation focuses on distinguishing viral from bacterial etiology using tools like the Centor criteria to guide antibiotic use.
Detail
Sore throat results from inflammation of the pharyngeal mucosa, commonly due to viral pathogens (rhinovirus, adenovirus, coronavirus, EBV) or bacterial infection, most notably Streptococcus pyogenes (Group A Strep, GAS). Viral pharyngitis typically presents with gradual onset, rhinorrhea, cough, and conjunctivitis, and is self-limited. GAS pharyngitis presents more abruptly with fever, tonsillar exudates, tender anterior cervical lymphadenopathy, and absence of cough (Centor criteria). Rapid antigen detection test (RADT) or throat culture confirms diagnosis. Treatment of GAS pharyngitis with antibiotics (penicillin or amoxicillin) reduces risk of suppurative complications (peritonsillar abscess, otitis media) and non-suppurative complications, notably acute rheumatic fever and post-streptococcal glomerulonephritis (PSGN)—high-yield for boards. Rheumatic fever prevention is the primary rationale for treating strep throat, as antibiotics do not significantly reduce PSGN risk. Other causes include infectious mononucleosis (EBV)—consider in adolescents with posterior cervical lymphadenopathy, splenomegaly, and atypical lymphocytes; gonococcal pharyngitis in sexually active patients; and diphtheria (grayish pseudomembrane) in unvaccinated populations. Peritonsillar abscess presents with trismus, uvular deviation, and muffled "hot potato" voice, requiring drainage. Epiglottitis (H. influenzae type b, now rare due to vaccination) is a pediatric emergency with high fever, drooling, and stridor. Chronic or unilateral sore throat with weight loss should raise concern for malignancy (e.g., nasopharyngeal carcinoma, especially EBV-associated) in adults.
Sources
- First Aid for the USMLE Step 1
- UpToDate: Pharyngitis in adults
- Centor RM et al., Medical Decision Making, 1981
- CDC Guidelines on Group A Streptococcal Pharyngitis
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