What is the recommended antibiotic for strep (streptococcal) pharyngitis?

Antibiotic Treatment for Streptococcal Pharyngitis

Penicillin or amoxicillin for 10 days is the first-line treatment for streptococcal pharyngitis due to their narrow spectrum of activity, infrequent adverse reactions, modest cost, and effectiveness in preventing acute rheumatic fever. 1

First-Line Treatment Options

Recommended Regimens:

• Penicillin V:

  • Children: 250 mg 2-3 times daily for 10 days
  • Adolescents/Adults: 500 mg 2-3 times daily for 10 days 1

• Amoxicillin:

  • 50 mg/kg once daily (maximum 1000 mg) OR
  • 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1

The 10-day course is mandatory for beta-lactam antibiotics to prevent acute rheumatic fever, which remains the primary objective of treatment as recommended by the American Academy of Pediatrics and the American Heart Association 1.

Alternative Options for Penicillin-Allergic Patients

For patients with penicillin allergy, treatment depends on the type of allergy:

• Non-anaphylactic allergy: First-generation cephalosporins for 10 days
• Anaphylactic allergy:
  • Clindamycin: 300-450 mg orally three times daily for 10 days
  • Azithromycin: 12 mg/kg once daily (max 500 mg) for 5 days
  • Clarithromycin 1

It's important to note that the FDA label for azithromycin specifically states: "Penicillin by the intramuscular route is the usual drug of choice in the treatment of Streptococcus pyogenes infection and the prophylaxis of rheumatic fever. Azithromycin is often effective in the eradication of susceptible strains of Streptococcus pyogenes from the nasopharynx. Because some strains are resistant to azithromycin, susceptibility tests should be performed when patients are treated with azithromycin." 2

Treatment Failures

Penicillin treatment failures occur in 5-35% of cases, potentially due to beta-lactamase-producing bacteria "shielding" the streptococci 1. For treatment failures, consider:

• Clindamycin
• Amoxicillin-clavulanate
• Cephalosporins 1

Important Clinical Considerations

Diagnosis

• Clinical features alone cannot reliably differentiate Group A Streptococcal (GAS) from viral pharyngitis
• Laboratory confirmation is necessary through Rapid Antigen Detection Test (RADT) or throat culture if RADT is negative 1
• Use Centor Criteria to guide testing decisions:
  1. Tonsillar exudates
  2. Tender anterior cervical lymph nodes
  3. Lack of cough
  4. Fever 1

Symptomatic Relief

• Analgesics/antipyretics (acetaminophen or NSAIDs) for pain and fever relief
• Throat lozenges and warm salt water gargles
• Cold liquids or ice chips
• Avoid hot liquids, spicy foods, and hard foods 1

Return to School/Work

• Patients should complete at least 24 hours of antibiotics before returning to school or work to reduce transmission risk 1

Pitfalls to Avoid

1. Inadequate duration of therapy: A full 10-day course of beta-lactam antibiotics is essential to prevent acute rheumatic fever, even if symptoms resolve earlier 1

2. Using macrolides as first-line therapy: Significant resistance to azithromycin and clarithromycin exists in some parts of the United States; these should be reserved for penicillin-allergic patients 1

3. Relying solely on clinical features for diagnosis: Laboratory confirmation is necessary, especially in children and adolescents 1

4. Treating without testing in low-risk patients: Patients with 0-2 Centor criteria are unlikely to have GAS infection and do not require testing or treatment 1

5. Neglecting to consider penicillin failure: If symptoms persist after 48-72 hours of antibiotic therapy, reevaluation is necessary 1