What is the best antibiotic choice for Group A Streptococcus (Strep A) infection?

From the Guidelines

Penicillin V is the recommended first-line antibiotic treatment for Group A Streptococcus (Strep A) infections, with a dosage of 250 mg twice daily or 3 times daily for children and 250 mg 4 times daily or 500 mg twice daily for adolescents and adults, for a duration of 10 days. This recommendation is based on the strongest and most recent evidence available, including the 2012 update by the Infectious Diseases Society of America 1. The use of penicillin V is supported by its high efficacy, narrow spectrum of activity, and cost-effectiveness.

Key Considerations

• For individuals without penicillin allergy, penicillin V, amoxicillin, and benzathine penicillin G are recommended as first-line treatments 1.
• For individuals with penicillin allergy, alternative treatments such as cephalexin, cefadroxil, clindamycin, azithromycin, and clarithromycin can be used, although the strength of recommendation may vary 1.
• It is essential to complete the full 10-day course of antibiotic treatment, even if symptoms improve earlier, to prevent complications like rheumatic fever.
• Accurate diagnosis of Strep A pharyngitis is crucial to prevent unnecessary antibiotic treatment and reduce the risk of antimicrobial resistance.

Treatment Options

• Penicillin V: 250 mg twice daily or 3 times daily for children, and 250 mg 4 times daily or 500 mg twice daily for adolescents and adults, for 10 days 1.
• Amoxicillin: 50 mg/kg once daily (max = 1000 mg) or 25 mg/kg twice daily (max = 500 mg) for 10 days 1.
• Benzathine penicillin G: 600,000 U for individuals <27 kg, and 1,200,000 U for individuals ≥27 kg, as a single dose 1.
• Alternative treatments for penicillin-allergic individuals: cephalexin, cefadroxil, clindamycin, azithromycin, and clarithromycin, with varying dosages and durations 1.

From the FDA Drug Label

Pharyngitis/tonsillitis caused by Streptococcus pyogenes as an alternative to first-line therapy in individuals who cannot use first-line therapy NOTE: 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. Data establishing efficacy of azithromycin in subsequent prevention of rheumatic fever are not available.

The best antibiotic choice for Strep A (Streptococcus pyogenes) is penicillin by the intramuscular route, as it is the usual drug of choice for the treatment of this infection and the prophylaxis of rheumatic fever.

• Azithromycin can be used as an alternative to first-line therapy in individuals who cannot use first-line therapy.
• Susceptibility tests should be performed when patients are treated with azithromycin, as some strains of Streptococcus pyogenes may be resistant to it 2.

From the Research

Antibiotic Choices for Strep A

• Penicillin and amoxicillin are first-line antibiotics for the treatment of group A beta-hemolytic streptococcal pharyngitis, with a recommended course of 10 days 3.
• First-generation cephalosporins are recommended for patients with nonanaphylactic allergies to penicillin 3.
• There is significant resistance to azithromycin and clarithromycin in some parts of the United States, making them less favorable options 3.
• A study comparing short-course antibiotic therapy with long-course antibiotic therapy found that short-course penicillin was less effective for early clinical cure and bacteriological eradication, while short-course macrolides and cephalosporins were equally effective or more effective than long-course penicillin 4.
• A systematic review and meta-analysis found that cephalosporins and macrolides may have similar efficacy to penicillin in treating group A streptococcal pharyngitis, but the evidence is uncertain and of low certainty 5, 6.
• Carbacephem may be more effective than penicillin for symptom resolution in children, but the evidence is limited and of low certainty 5, 6.
• All isolates of group A Streptococcus were susceptible to β-lactams, including penicillin, in a study of invasive group A Streptococcus infections in the United States 7.

Resistance Patterns

• There is increasing prevalence of erythromycin-nonsusceptible and clindamycin-nonsusceptible group A Streptococcus infections in the United States, particularly among certain emm types and in certain populations 7.
• Clinicians should consider local resistance patterns when treating group A Streptococcus infections 7.