Treatment for Streptococcal Infections
First-Line Treatment: Penicillin or Amoxicillin
For confirmed Group A streptococcal infections, penicillin V or amoxicillin for 10 full days is the treatment of choice due to proven efficacy in preventing acute rheumatic fever, zero documented resistance worldwide, narrow spectrum, safety profile, and low cost. 1, 2, 3
Specific Dosing Regimens
Adults:
- Penicillin V: 500 mg orally twice daily for 10 days 2
- Amoxicillin: 500 mg orally twice daily OR 875 mg twice daily for 10 days 3
Children (≥3 months and <40 kg):
- Penicillin V: 250 mg orally 2-3 times daily for 10 days 2
- Amoxicillin: 50 mg/kg once daily (maximum 1000 mg) OR 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 2, 3
- Amoxicillin is preferred over penicillin V in young children due to better palatability 2
The 10-day duration is mandatory—it cannot be shortened despite clinical improvement after 3-4 days, as this dramatically increases treatment failure rates and risk of acute rheumatic fever. 1, 2, 3
Treatment for Penicillin-Allergic Patients
Non-Immediate (Non-Anaphylactic) Penicillin Allergy
First-generation cephalosporins are the preferred alternative, with only 0.1% cross-reactivity risk in patients with delayed, non-severe reactions. 4, 2
Recommended regimens:
- Cephalexin: 500 mg orally twice daily for 10 days (adults) OR 20 mg/kg per dose twice daily for 10 days (children, maximum 500 mg/dose) 4, 2
- Cefadroxil: 1 gram orally once daily for 10 days (adults) OR 30 mg/kg once daily for 10 days (children, maximum 1 gram) 4, 2
Immediate/Anaphylactic Penicillin Allergy
All beta-lactam antibiotics must be avoided due to up to 10% cross-reactivity risk with cephalosporins in patients with immediate hypersensitivity reactions (anaphylaxis, angioedema, urticaria within 1 hour). 4, 2
Clindamycin is the preferred choice with only ~1% resistance among Group A Streptococcus in the United States and superior eradication rates even in chronic carriers. 4, 2, 5
Recommended regimens:
- Clindamycin: 300 mg orally three times daily for 10 days (adults) OR 7 mg/kg per dose three times daily for 10 days (children, maximum 300 mg/dose) 4, 2, 5
Alternative macrolides (use only if clindamycin cannot be used):
- Azithromycin: 500 mg orally once daily for 5 days (adults) OR 12 mg/kg once daily for 5 days (children, maximum 500 mg)—the ONLY antibiotic requiring just 5 days due to prolonged tissue half-life 4, 2
- Clarithromycin: 250 mg orally twice daily for 10 days (adults) OR 7.5 mg/kg per dose twice daily for 10 days (children, maximum 250 mg/dose) 4, 2
Important caveat: Macrolide resistance is 5-8% in the United States and varies geographically, making clindamycin more reliable when beta-lactams cannot be used. 4, 2
Critical Treatment Principles
Why 10 Days Matters
The primary goal is preventing acute rheumatic fever, which requires complete pharyngeal eradication of Group A Streptococcus—achievable only with a full 10-day course (except azithromycin's unique 5-day regimen). 1, 2, 3 Therapy can be safely postponed up to 9 days after symptom onset and still prevent rheumatic fever, but once started, the full course must be completed. 1
Secondary Goals
- Prevent suppurative complications (peritonsillar abscess, cervical lymphadenitis, mastoiditis) 2
- Reduce symptom duration by 1-2 days (modest benefit with number needed to treat of 6 at 3 days) 1
- Decrease contagion (patients become non-infectious after 24 hours of appropriate antibiotics) 6
Common Pitfalls to Avoid
Never prescribe shorter courses than recommended (except azithromycin's 5-day regimen)—even a few days' reduction dramatically increases treatment failure and rheumatic fever risk. 4, 2
Do not use cephalosporins in patients with immediate/anaphylactic penicillin reactions due to 10% cross-reactivity risk. 4, 2
Avoid trimethoprim-sulfamethoxazole (Bactrim) entirely—it does not eradicate Group A Streptococcus and has no role in treating streptococcal pharyngitis. 4
Do not routinely retest asymptomatic patients after treatment completion—this leads to unnecessary retreatment of chronic carriers who are at low risk for complications and transmission. 4, 2
Be aware of local macrolide resistance patterns before prescribing azithromycin or clarithromycin, as resistance can exceed 10% in some geographic areas. 4, 2
Special Clinical Situations
Treatment Failures or Recurrent Infections
For patients who fail initial penicillin/amoxicillin therapy or have multiple recurrences, clindamycin demonstrates substantially higher eradication rates than penicillin in eliminating chronic streptococcal carriage. 4, 2
Alternative regimens for treatment failures:
- Clindamycin 300 mg orally three times daily for 10 days 4, 2
- Amoxicillin-clavulanate 40 mg amoxicillin/kg/day in 3 doses for 10 days (maximum 2000 mg amoxicillin/day) 4
Chronic Carriers
Chronic carriers (asymptomatic patients with persistently positive cultures) generally do not require treatment, as they are unlikely to spread infection or develop complications. 2 Consider treatment only in special circumstances: community outbreak of rheumatic fever, family history of rheumatic fever, or multiple household members with repeated infections. 4
Severe Invasive Infections
For necrotizing fasciitis and streptococcal toxic shock syndrome, combination therapy with penicillin PLUS clindamycin is mandatory. 1, 4 Clindamycin suppresses production of streptococcal pyrogenic exotoxins and modulates cytokine production, providing benefits beyond antimicrobial activity. 4
Recommended dosing: Penicillin 2-4 million units IV every 4-6 hours PLUS clindamycin 600-900 mg IV every 8 hours. 4
Adjunctive Symptomatic Treatment
Acetaminophen or NSAIDs (ibuprofen) should be offered for moderate to severe symptoms or high fever. 4, 2 Aspirin must be avoided in children due to Reye syndrome risk. 4, 2 Corticosteroids are not recommended as adjunctive therapy. 4