Infectious Disease · Upper Respiratory Infections
The facts most likely to be tested
Rhinovirus, coronavirus, and adenovirus are the most common viral etiologies of acute pharyngitis.
The presence of coryza, conjunctivitis, cough, and hoarseness strongly suggests a viral etiology rather than Group A Streptococcus.
Centor criteria are used to estimate the probability of Group A Streptococcus (GAS), with viral pharyngitis typically scoring low due to the absence of tonsillar exudates and tender anterior cervical lymphadenopathy.
Supportive care including analgesics and antipyretics is the definitive management for viral pharyngitis.
Antibiotics are strictly contraindicated in viral pharyngitis as they provide no clinical benefit and increase the risk of adverse drug reactions and antibiotic resistance.
Adenoviral pharyngitis is uniquely associated with pharyngoconjunctival fever, characterized by the triad of pharyngitis, fever, and conjunctivitis.
Monospot testing or EBV-specific serology is indicated if the patient presents with posterior cervical lymphadenopathy, splenomegaly, and atypical lymphocytosis.
Vignette unlocked
A 22-year-old college student presents to the urgent care clinic with a 3-day history of sore throat, nasal congestion, and a mild non-productive cough. Physical examination reveals erythematous oropharyngeal mucosa without tonsillar exudates. The patient has bilateral conjunctival injection and clear rhinorrhea. There is no significant cervical lymphadenopathy. Temperature is 99.2°F (37.3°C).
What is the most appropriate management for this patient?
Supportive care with analgesics and fluids
The presence of cough, coryza, and conjunctivitis strongly points to a viral etiology, making antibiotic therapy unnecessary and inappropriate according to the Centor criteria.
Full handout
High yield triage
Etiology / Epidemiology
Most common cause of pharyngitis; Adenovirus is the most frequent viral pathogen in adults.
Clinical Manifestations
Presents with coryza, conjunctivitis, and cough; absence of exudates favors viral etiology.
Diagnosis
Clinical diagnosis; Centor criteria used to exclude Group A Strep (GAS) and avoid unnecessary testing.
Treatment
Management is supportive care; avoid antibiotics as they provide no benefit in viral illness.
Prognosis
Self-limiting; symptoms typically resolve within 7-10 days.
Full handout
Epidemiology & Etiology
Viral pharyngitis accounts for >80% of all sore throat cases. Common pathogens include Adenovirus, Rhinovirus, Coronavirus, and Influenza. It is highly contagious, spreading via respiratory droplets in crowded environments like schools or barracks.
Pertinent Anatomy
Infection involves the pharyngeal mucosa and lymphoid tissue of the Waldeyer's ring. Inflammation leads to localized edema and hyperemia of the tonsillar pillars and posterior pharynx.
Pathophysiology
Viral invasion of the respiratory epithelium triggers a local inflammatory response, causing vasodilation and increased vascular permeability. This results in the classic triad of sore throat, erythema, and edema. Systemic symptoms arise from the release of inflammatory cytokines.
Clinical Manifestations
Patients typically present with coryza, hoarseness, cough, and conjunctivitis (highly suggestive of Adenovirus). The presence of ulcers or vesicles suggests Herpangina or Hand-foot-and-mouth disease. Red flags include drooling, stridor, or muffled voice, which suggest a peritonsillar abscess or epiglottitis.
Diagnosis
Diagnosis is primarily clinical. Use the Centor criteria to assess the probability of GAS; a score of 0-1 indicates no testing is required. The Rapid Antigen Detection Test (RADT) is the gold standard if bacterial pharyngitis is suspected, but it is not indicated for classic viral presentations.
Treatment
Treatment is strictly supportive care including hydration, salt-water gargles, and NSAIDs or acetaminophen for pain. Antibiotics are strictly contraindicated as they do not shorten the course and increase the risk of Clostridioides difficile infection. Topical anesthetics may provide temporary relief.
Prognosis
The condition is self-limiting with a duration of 7-10 days. Complications are rare but include secondary bacterial infection or dehydration if oral intake is severely limited.
Differential Diagnosis
Group A Strep: presence of tonsillar exudates and tender anterior cervical lymphadenopathy
Infectious Mononucleosis: posterior cervical lymphadenopathy and hepatosplenomegaly
Peritonsillar Abscess: uvular deviation and 'hot potato' voice
Epiglottitis: drooling, tripod positioning, and rapid onset
Diphtheria: thick, gray, adherent pseudomembrane