Streptococcal pharyngitis, or strep throat, is an acute infection and inflammation of the pharynx that affects both children and adults. The most common bacterial etiology of pharyngitis is group A beta-hemolytic Streptococcus (GABHS, or Streptococcus pyogenes). The infection is transmitted via respiratory secretions.

Demographics:

• Responsible for 5%-20% of cases of pharyngitis in adults.
• Responsible for 15%-30% of cases of pharyngitis in children.
• Most commonly occurs in children between ages 5 and 15 years.

Symptoms (Often Abrupt Onset):
Typical

• Sore throat, pain or difficulty swallowing
• Fever
• Chills
• Malaise
• Headache – frequently frontal in location

Variants

• Younger children – abdominal pain, nausea, and vomiting
• Severe unilateral throat pain should raise concern for a peritonsillar or retropharyngeal abscess, especially if this symptom arises or progresses several days after onset of symptoms. Inability to swallow, or odynophagia, should raise concern for a peritonsillar or retropharyngeal abscess.

Signs:
Typical

• Pharyngeal erythema
• Exudate (gray-white), tonsillar pillars or posterior pharynx; occasional palatine petechiae, erythema and edema of the uvula, enlarged tonsils 
• Anterior cervical lymphadenopathy (classic angle of jaw)

Variants

• Scarlet fever – Usually face-sparing, punctate, erythematous, blanchable, sandpaper-like exanthem that may be accentuated in skin folds and creases (Pastia's lines) and may desquamate during convalescence; bright red tongue with inflamed papillae (strawberry tongue); erythematous pharynx and tonsils covered with exudate.
• Children younger than 3 years – Coryza, purulent nasal discharge, excoriated nares (streptococcosis), and generalized adenopathy.

Risk Factors:

• Exposure to a person with known streptococcal pharyngitis.
• History of acute rheumatic fever or rheumatic heart disease.

Timeline:

• The incubation period is 24-72 hours.
• In most people, fever resolves within 3-5 days and throat pain resolves within 1 week, even without specific treatment.
• Patients with untreated GABHS pharyngitis are infectious during the acute phase and for 1 week after.
• Late winter and early spring are peak GABHS seasons.

Complications of GABHS Illness:
Suppurative

• Bacteremia
• Cervical lymphadenitis
• Endocarditis
• Fasciitis / myositis
• Mastoiditis
• Meningitis
• Otitis media
• Perianal dermatitis in children
• Peritonsillar / retropharyngeal abscess (quinsy) – Patient has toxic appearance, "hot potato voice," fluctuant peritonsillar mass, and asymmetric deviation of the uvula.
• Pneumonia
• Sinusitis
• Toxic shock

Nonsuppurative

• Poststreptococcal glomerulonephritis – Hematuria and edema with history of a recent streptococcal infection (elevated anti-streptolysin O titer).
• Acute rheumatic fever – Major (carditis, polyarthritis, chorea, erythema marginatum, subcutaneous nodules) and minor (arthralgias, fever, elevated acute-phase reactants, prolonged PR interval).
• Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS).
• Poststreptococcal autoimmune dystonia secondary to striatal necrosis.
• Poststreptococcal reactive arthritis.
• Sydenham chorea and other autoimmune movement disorders.