Streptococcal pharyngitis
Streptococcal pharyngitis is an acute infection of the tonsils and pharynx caused by group A Streptococcus pyogenes, presenting with rapid-onset sore throat, fever, tonsillar exudates, and tender anterior cervical lymphadenopathy without cough; diagnosis relies on the Centor criteria to guide rapid antigen testing, and treatment with penicillin or amoxicillin prevents suppurative complications and acute rheumatic fever.
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What this article covers
- Overview
An acute bacterial infection of the tonsils and pharynx caused by group A Streptococcus pyogenes, accounting for only 5% to 15% of all acute pharyngitis, the great majority of which is viral.
- Epidemiology
Most common in school-age children, particularly ages 6 to 12 years, though it occurs in children over age 3 and in adults; it is uncommon under age 3.
- Risk factors
Age 5 to 15 years, the peak incidence range for group A streptococcal pharyngitis.
- Pathophysiology
Streptococcus pyogenes, a gram-positive coccus growing in chains, adheres to and infects the tonsillar and pharyngeal epithelium, producing local pyogenic inflammation.
- Clinical features
Rapid onset of throat pain and fever, typically with a temperature greater than 38.3°C, is the defining presentation, developing over hours to a day or two rather than gradually.
- Differential diagnosis
Peritonsillar abscess: a "hot potato" muffled voice, trismus, uvular deviation away from the affected side, and pain markedly worse on one side with referred otalgia; requires drainage in addition to antibiotics.
- Diagnosis
Streptococcal pharyngitis is confirmed by a positive rapid antigen detection test (RADT) or throat culture in a patient with a compatible clinical picture; the Centor criteria determine who should be…
- Management
First, confirm the diagnosis with a positive RADT or throat culture before starting antibiotics, reserving treatment for confirmed cases rather than treating empirically.
- Complications
Peritonsillar abscess: the most common suppurative complication, with unilateral throat pain, trismus, and uvular deviation, requiring drainage.
- Prognosis
Uncomplicated streptococcal pharyngitis resolves fully with appropriate antibiotic treatment, with symptoms typically improving within 24 to 48 hours of starting therapy.
- Prevention
Give a full 10-day course of a first-line antibiotic (amoxicillin or penicillin V) for every confirmed case, since completing the full course, not merely starting treatment, reduces the risk of acute rheumatic fever.
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