What is the drug of choice and recommended dosing for Streptococcus infections in a healthy adult or child without a penicillin allergy?

Drug of Choice for Streptococcus Infections

Penicillin V (500 mg orally twice daily for 10 days) or amoxicillin (50 mg/kg once daily, maximum 1000 mg, for 10 days) are the drugs of choice for streptococcal infections in patients without penicillin allergy. 1

Why Penicillin Remains First-Line

• Penicillin has been the gold standard for treating Group A Streptococcus for over 40 years, with proven efficacy in preventing acute rheumatic fever, no documented resistance anywhere in the world, narrow spectrum of activity, excellent safety profile, and low cost. 2, 1

• Amoxicillin is equally effective and often preferred over penicillin V due to better palatability (especially in children), availability as suspension, and the convenience of once-daily dosing. 1

• Both penicillin V and amoxicillin require a full 10-day course to achieve maximal pharyngeal eradication and prevent acute rheumatic fever—shortening the course by even a few days dramatically increases treatment failure rates. 2, 1

Specific Dosing Regimens

Adults and Children ≥12 Years

• Penicillin V: 500 mg orally twice daily for 10 days 1, 3
• Amoxicillin: 1000 mg once daily for 10 days 1

Children <12 Years

• Penicillin V: 250 mg (or calculated as appropriate for weight) every 6-8 hours for 10 days 3
• Amoxicillin: 50 mg/kg once daily (maximum 1000 mg) for 10 days, or 20 mg/kg twice daily (maximum 500 mg per dose) 1

When Compliance Is Uncertain

• Intramuscular benzathine penicillin G: 600,000 units if <27 kg; 1,200,000 units if ≥27 kg as a single dose ensures complete treatment when adherence to oral therapy cannot be assured. 1

Alternatives for Penicillin-Allergic Patients

Non-Immediate (Delayed) Penicillin Allergy

• First-generation cephalosporins are the preferred alternatives, with only 0.1% cross-reactivity risk in patients with delayed reactions such as mild rash. 2, 4
• Cephalexin 500 mg orally twice daily for 10 days (adults) or 20 mg/kg per dose twice daily (maximum 500 mg/dose) for 10 days (children) 2, 1
• Cefadroxil 1 gram once daily for 10 days (adults) or 30 mg/kg once daily for 10 days (children) is an alternative. 2

Immediate/Anaphylactic Penicillin Allergy

• All beta-lactam antibiotics must be avoided due to up to 10% cross-reactivity risk with cephalosporins in patients who experienced anaphylaxis, angioedema, respiratory distress, or urticaria within 1 hour of penicillin administration. 2, 4

• Clindamycin is the preferred choice: 300 mg orally three times daily for 10 days (adults) or 7 mg/kg per dose three times daily (maximum 300 mg/dose) for 10 days (children). 2, 1

• Clindamycin has only ~1% resistance among Group A Streptococcus in the United States and demonstrates superior efficacy in chronic carriers and treatment failures. 2, 4

• Azithromycin 500 mg once daily for 5 days (adults) or 12 mg/kg once daily (maximum 500 mg) for 5 days (children) is an acceptable alternative, but macrolide resistance is 5-8% in the United States and varies geographically. 2, 1

• Azithromycin is the only antibiotic requiring just 5 days due to its prolonged tissue half-life; all other antibiotics require the full 10 days. 2, 1

Critical Pitfalls to Avoid

• Never use cephalosporins in patients with immediate/anaphylactic penicillin reactions (anaphylaxis, angioedema, immediate urticaria)—the 10% cross-reactivity risk makes this dangerous. 2, 1

• Never prescribe courses shorter than 10 days (except azithromycin's 5-day regimen)—this leads to treatment failure and increased risk of acute rheumatic fever. 2, 1

• Trimethoprim-sulfamethoxazole (Bactrim) is absolutely contraindicated for streptococcal pharyngitis because it fails to eradicate Group A Streptococcus in 20-25% of cases. 2

• Do not use broad-spectrum cephalosporins (cefuroxime, cefdinir, cefpodoxime) when narrow-spectrum first-generation agents are appropriate—they are more expensive and promote resistant flora. 2

Adjunctive Symptomatic Treatment

• Acetaminophen or NSAIDs (such as ibuprofen) should be offered for moderate to severe symptoms or high fever. 2, 1

• Aspirin must be avoided in children due to the risk of Reye syndrome. 2, 1

• Corticosteroids are not recommended as adjunctive therapy. 2

Special Clinical Situations

Recurrent Infections or Treatment Failures

• Clindamycin is substantially more effective than penicillin in eliminating chronic streptococcal carriage: 300 mg three times daily for 10 days (adults) or 20-30 mg/kg/day for 10 days (children). 2, 1, 4

• Amoxicillin-clavulanate 40 mg/kg/day in 3 divided doses for 10 days (maximum 750 mg amoxicillin per day) is an alternative. 1

When to Consider Chronic Carrier Status

• Chronic carriers generally do not require treatment—they are unlikely to spread infection and are at very low risk for complications. 2
• Consider carrier status in patients with multiple "recurrent" infections who may actually be experiencing viral pharyngitis superimposed on chronic colonization. 2, 4