What is the first-line antibiotic treatment for a typical case of strep throat (Group A beta-hemolytic Streptococcus) in adults and children?

First-Line Antibiotic for Strep Throat

Penicillin or amoxicillin is the number one antibiotic for strep throat in both adults and children, with no documented resistance worldwide and proven efficacy in preventing acute rheumatic fever. 1

Why Penicillin/Amoxicillin is First-Line

• Penicillin remains the treatment of choice due to its proven efficacy, safety, narrow spectrum of activity, and low cost. 1
• No resistance to penicillin has been documented anywhere in the world among Group A streptococci, making it uniquely reliable. 1
• Both penicillin and amoxicillin are FDA-approved for treatment of infections due to susceptible Streptococcus species (α- and β-hemolytic isolates only). 2

Specific Dosing Regimens

Adults

• Penicillin V: 250 mg orally three times daily for 10 days OR 500 mg twice daily for 10 days 1
• Amoxicillin: 500 mg orally twice daily for 10 days (often preferred for better compliance) 1
• Benzathine penicillin G: Single intramuscular injection (for compliance concerns) 1

Children (≥3 months)

• Amoxicillin: 50 mg/kg once daily (maximum 1,000 mg) OR 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 3
• Amoxicillin is often preferred in young children due to better taste acceptance of the suspension. 3

Critical Treatment Duration

• A complete 10-day course is mandatory to achieve maximal pharyngeal eradication of Group A Streptococcus and prevent acute rheumatic fever. 1
• Treatment can be initiated up to 9 days after symptom onset and still prevent rheumatic fever. 1
• Do not shorten the course below 10 days, even if symptoms improve rapidly—this dramatically increases treatment failure and rheumatic fever risk. 1

Alternatives for Penicillin Allergy

Non-Immediate (Non-Anaphylactic) Penicillin Allergy

• First-generation cephalosporins are preferred alternatives, with only 0.1% cross-reactivity risk in patients with non-severe delayed reactions. 1
• 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, 1

Immediate/Anaphylactic Penicillin Allergy

• Clindamycin is the preferred choice, with approximately 1% resistance rate in the United States. 4
• 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
• Azithromycin: 500 mg 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
• Macrolide resistance is 5-8% in the United States, making clindamycin more reliable. 4

Common Pitfalls to Avoid

• Do not use cephalosporins in patients with immediate hypersensitivity (anaphylaxis, angioedema, immediate urticaria) to penicillin—up to 10% cross-reactivity risk exists. 4, 1
• Do not prescribe trimethoprim-sulfamethoxazole (Bactrim) for strep throat—it has high resistance rates and is not effective against Group A Streptococcus. 4
• Do not use broad-spectrum antibiotics when narrow-spectrum penicillin is appropriate—this unnecessarily increases antibiotic resistance. 4
• Physicians overdiagnose streptococcal pharyngitis by a wide margin, leading to unnecessary antibiotic use—confirm diagnosis with rapid antigen detection testing or throat culture. 5

Adjunctive Therapy

• Acetaminophen or NSAIDs (such as ibuprofen) should be considered for moderate to severe symptoms or high fever. 1
• Avoid aspirin in children due to risk of Reye syndrome. 1
• Corticosteroids are not recommended as adjunctive therapy. 4