What is the recommended treatment for strep throat and what are the differential diagnoses?

Treatment for Streptococcal Pharyngitis and Differential Diagnoses

Penicillin or amoxicillin is the recommended first-line treatment for Group A Streptococcal (GAS) pharyngitis due to their narrow spectrum of activity, infrequency of adverse reactions, and modest cost. 1

First-Line Treatment for GAS Pharyngitis

• Oral penicillin V for 10 days is the treatment of choice for patients with confirmed GAS pharyngitis 1

  • Children: 250 mg twice or three times daily for 10 days 1
  • Adolescents and adults: 250 mg three or four times daily, or 500 mg twice daily for 10 days 1

• Amoxicillin is often used in place of penicillin V, particularly for young children, due to better taste acceptance and once-daily dosing option 1

  • Recommended dosage: 50 mg/kg once daily (maximum 1000 mg) for 10 days 1
  • FDA label indicates at least 10 days of treatment is required for any infection caused by Streptococcus pyogenes to prevent acute rheumatic fever 2

• Intramuscular benzathine penicillin G (1.2 million units as a single dose) is preferred for patients unlikely to complete the full 10-day oral regimen 1

Treatment for Penicillin-Allergic Patients

• For patients with non-anaphylactic penicillin allergy: First-generation cephalosporins for 10 days 1, 3

• For patients with anaphylactic penicillin allergy, options include: 1, 3

  • Clindamycin: 7 mg/kg per dose three times daily (maximum 300 mg per dose) for 10 days
  • Clarithromycin: 7.5 mg/kg per dose twice daily (maximum 250 mg per dose) for 10 days
  • Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days

Management of Recurrent GAS Pharyngitis

• For patients with multiple recurrences, consider whether they are experiencing true recurrent infections or are chronic carriers with viral infections 1, 3

• Treatment options for documented recurrent GAS pharyngitis: 1

  • Clindamycin: 20-30 mg/kg/day in 3 divided doses for 10 days
  • Amoxicillin-clavulanic acid: 40 mg/kg/day in 3 divided doses for 10 days
  • Benzathine penicillin G with rifampin (added during the final 4 days)

Adjunctive Therapy

• Acetaminophen or NSAIDs are recommended for moderate to severe symptoms or fever control 1, 3

• Aspirin should be avoided in children due to risk of Reye syndrome 1, 3

• Corticosteroids are not recommended for routine use 1

Differential Diagnosis of Pharyngitis

Viral Pharyngitis

• Most common cause of pharyngitis (70-85% of cases) 4, 5
• Clinical features suggesting viral etiology: 1, 4
  • Cough
  • Rhinorrhea (runny nose)
  • Hoarseness
  • Oral ulcers
  • Conjunctivitis
  • Diarrhea

Bacterial Causes

• Group A Streptococcus (S. pyogenes) - most common bacterial cause 1
• Features suggesting GAS: 1, 5
  • Sudden onset of sore throat
  • Fever
  • Tonsillar exudate
  • Tender anterior cervical lymphadenopathy
  • Absence of cough
  • Patient age 3-15 years
• Other bacterial causes: 1
  • Group C and G streptococci
  • Neisseria gonorrhoeae
  • Corynebacterium diphtheriae
  • Arcanobacterium haemolyticum

Other Causes

• Fungal (e.g., Candida) - especially in immunocompromised patients 4
• Non-infectious causes (e.g., allergies, acid reflux, environmental irritants) 4

Common Pitfalls to Avoid

• Overdiagnosis and overtreatment of viral pharyngitis as bacterial infection 3, 4
• Failure to complete the full 10-day course of penicillin or amoxicillin, which can lead to treatment failure and increased risk of rheumatic fever 1, 6
• Using macrolides (azithromycin, clarithromycin) in areas with high resistance rates 3, 5
• Failing to distinguish between true recurrent infections and chronic carriage with viral infections 1, 3
• Unnecessary tonsillectomy solely to reduce frequency of GAS pharyngitis 3

Testing Recommendations

• Diagnosis should be confirmed by rapid antigen detection test (RADT) or throat culture before prescribing antibiotics 1
• In children and adolescents, negative RADT tests should be backed up by a throat culture 1
• Testing is not recommended for patients with clinical features strongly suggesting viral etiology 1