What is the first-line treatment for a patient diagnosed with strep pharyngitis?

First-Line Treatment for Strep Pharyngitis

Penicillin V or amoxicillin for 10 days is the first-line treatment for strep pharyngitis. 1

Why Penicillin/Amoxicillin Remains First-Line

Penicillin remains the treatment of choice based on proven efficacy, safety, narrow spectrum of activity, and low cost. 1 Critically, penicillin-resistant Group A Streptococcus has never been documented anywhere in the world. 1

Specific dosing regimens:

• Penicillin V: 250 mg four times daily or 500 mg twice daily for adolescents/adults for 10 days 2
• Amoxicillin: 50 mg/kg once daily (maximum 1,000 mg) for children, or 500 mg twice daily for adults, for 10 days 1, 2

Amoxicillin is often preferred over penicillin V in young children primarily due to better palatability of the suspension, though efficacy is equal. 1

Critical Treatment Duration

A full 10-day course is mandatory to achieve maximal pharyngeal eradication of Group A Streptococcus and prevent acute rheumatic fever. 1, 2 Shortening the course by even a few days results in appreciable increases in treatment failure rates. 2 This requirement is supported by strong, high-quality evidence from the 2012 IDSA guidelines. 1

Research confirms that short-course penicillin (≤5 days) is significantly less effective than long-course penicillin for both clinical cure (OR 0.43) and bacteriological eradication (OR 0.34). 3

Alternatives for Penicillin-Allergic Patients

Non-Immediate/Non-Anaphylactic Penicillin Allergy

First-generation cephalosporins are the preferred alternative with strong, high-quality evidence. 1, 4

• Cephalexin: 500 mg twice daily for adults (20 mg/kg/dose twice daily for children, maximum 500 mg/dose) for 10 days 4
• Cefadroxil: 1 gram once daily for adults (30 mg/kg once daily for children, maximum 1 gram) for 10 days 1, 4

The cross-reactivity risk with first-generation cephalosporins is only 0.1% in patients with non-severe, delayed penicillin reactions. 4

Immediate/Anaphylactic Penicillin Allergy

Avoid all beta-lactam antibiotics including cephalosporins due to up to 10% cross-reactivity risk. 1, 4

Clindamycin is the preferred choice with strong, moderate-quality evidence:

• Dosing: 300 mg three times daily for adults (7 mg/kg/dose three times daily for children, maximum 300 mg/dose) for 10 days 1, 4
• Resistance: Only approximately 1% among Group A Streptococcus in the United States 1, 4
• Advantage: Demonstrates substantially higher eradication rates in chronic carriers and treatment failures 4

Macrolide alternatives (less preferred):

• Azithromycin: 500 mg once daily for 5 days in adults (12 mg/kg once daily for children, maximum 500 mg) 1, 4
• Clarithromycin: 250 mg twice daily for 10 days in adults (7.5 mg/kg/dose twice daily for children, maximum 250 mg/dose) 1, 4
• Concern: Macrolide resistance is 5-8% in the United States and varies geographically 1, 4

The FDA label for azithromycin explicitly states that "penicillin by the intramuscular route is the usual drug of choice" and notes that "data establishing efficacy of azithromycin in subsequent prevention of rheumatic fever are not available." 5

Common Pitfalls to Avoid

• Do not use trimethoprim-sulfamethoxazole (Bactrim): It has a 50% resistance rate and fails to eradicate Group A Streptococcus. 4, 2
• Do not use tetracyclines or sulfonamides: High prevalence of resistant strains makes them ineffective. 4
• Do not prescribe cephalosporins to patients with anaphylaxis, angioedema, or immediate urticaria to penicillin: The 10% cross-reactivity risk is unacceptable. 1, 4
• Do not shorten treatment duration below 10 days (except azithromycin's 5-day course): This dramatically increases treatment failure and rheumatic fever risk. 1, 2
• Do not use broad-spectrum cephalosporins (cefdinir, cefpodoxime) when narrow-spectrum first-generation agents are appropriate: They are more expensive and select for resistant flora. 4

Adjunctive Symptomatic Treatment

• Acetaminophen or NSAIDs (ibuprofen) for moderate to severe symptoms or high fever 1, 2
• Avoid aspirin in children due to Reye syndrome risk 1, 2
• Corticosteroids are not recommended 1, 2

Post-Treatment Considerations

Routine follow-up throat cultures or rapid antigen detection tests are not recommended for asymptomatic patients who have completed therapy. 1 Testing should only be considered in special circumstances, such as patients with a history of rheumatic fever. 1, 4