What is the appropriate treatment for a patient diagnosed with Group A Streptococcus infection?

Treatment of Group A Streptococcus Infection

Penicillin V or amoxicillin for 10 days is the definitive first-line treatment for Group A Streptococcus pharyngitis, with penicillin remaining the gold standard due to its proven efficacy, safety, narrow spectrum, and complete absence of resistance worldwide. 1, 2, 3

First-Line Antibiotic Regimens for Patients Without Penicillin Allergy

Oral Penicillin V (10 days): 1, 2, 3

• Children: 250 mg twice or three times daily 1, 2
• Adolescents and adults: 250 mg four times daily OR 500 mg twice daily 1, 2
• Must complete full 10-day course to prevent acute rheumatic fever 2, 3, 4, 5

Oral Amoxicillin (10 days): 1, 2, 3

• 50 mg/kg once daily (maximum 1,000 mg) OR 25 mg/kg twice daily (maximum 500 mg) 1, 2, 3
• Preferred in young children due to better taste acceptance of suspension 1, 2
• Efficacy equal to penicillin V 1, 2

Intramuscular Benzathine Penicillin G (single dose): 1, 3

• Patients <60 lbs (27 kg): 600,000 units 1, 3
• Patients ≥60 lbs: 1,200,000 units 1, 3
• Use this regimen when compliance with 10-day oral therapy is questionable 1, 3

Alternative Regimens for Penicillin-Allergic Patients

For non-immediate hypersensitivity (no anaphylaxis, angioedema, or urticaria): 1, 2, 3

• First-generation cephalosporins for 10 days 1, 2
• Cephalexin: 20 mg/kg/dose twice daily (maximum 500 mg per dose) 1
• Cefadroxil: 30 mg/kg once daily (maximum 1 g) 1
• Cross-reactivity risk with penicillin is <3% 6

For immediate-type hypersensitivity (anaphylaxis, angioedema, urticaria): 1, 2, 3

• Clindamycin: 7 mg/kg/dose three times daily (maximum 300 mg per dose) for 10 days 1, 2, 7
• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 1
• Clarithromycin: 7.5 mg/kg/dose twice daily (maximum 250 mg per dose) for 10 days 1

Critical caveat: Macrolide resistance (azithromycin, clarithromycin) varies geographically and temporally, with <5% resistance in the United States but higher rates reported elsewhere. 1, 2, 3 Do not use macrolides in areas with known high resistance rates. 8

Treatment of Invasive Group A Streptococcus Infections (Bacteremia, Necrotizing Fasciitis, Toxic Shock Syndrome)

Initial empiric therapy before organism identification: 6

• Vancomycin or linezolid PLUS piperacillin-tazobactam or carbapenem 6
• Broad-spectrum coverage is essential as etiology may be polymicrobial 6

Definitive therapy once GAS confirmed: 6

• Penicillin G 12-24 million units/day IV PLUS clindamycin 600-900 mg IV every 8 hours 6
• Never use penicillin monotherapy for necrotizing fasciitis or toxic shock syndrome—clindamycin addition is life-saving by suppressing toxin production 6
• Surgical consultation must not be delayed when necrotizing infection is suspected 6

For penicillin allergy in invasive infections: 6

• Non-immediate hypersensitivity: Cefazolin 6
• Immediate hypersensitivity: Clindamycin (preferred) or vancomycin 6

Primary Treatment Goals (In Order of Priority)

1. Prevent acute rheumatic fever (most critical for mortality and morbidity) 2, 3
2. Prevent suppurative complications (peritonsillar abscess, cervical lymphadenitis, mastoiditis) 2
3. Reduce symptom duration and transmission 2

Management of Household Contacts

Do not routinely test or treat asymptomatic household contacts. 1, 2 Approximately 25% of household contacts harbor GAS asymptomatically but are at low risk for complications. 1, 2

Exceptions requiring contact testing and treatment: 1

• Documented outbreak in closed/partially closed community 1
• Family or personal history of acute rheumatic fever 1
• Excessive anxiety about GAS infections 1

Management of Chronic Carriers

GAS carriers do not require identification efforts or antimicrobial therapy as they are unlikely to spread infection or develop complications. 2 Carriers are defined as patients with persistently positive throat cultures without clinical symptoms. 1

If treatment of carrier state is necessary (rare indications): 1

• Clindamycin 20-30 mg/kg/day in three doses (maximum 300 mg per dose) for 10 days 1
• Penicillin V plus rifampin for 10 days (rifampin added for last 4 days) 1
• Amoxicillin/clavulanate 40 mg amoxicillin/kg/day in three doses for 10 days 1

Management of Recurrent Episodes

Treat recurrent episodes with the same antimicrobial agents appropriate for initial illness. 2 For multiple recurrences, consider clindamycin or amoxicillin/clavulanate as they achieve higher pharyngeal eradication rates in carrier states. 2, 3

Critical Pitfalls to Avoid

Never use shorter antibiotic courses (<10 days for oral therapy) despite some literature suggesting efficacy, as this increases the risk of rheumatic fever. 2, 3 The 10-day duration is essential for maximal pharyngeal eradication and prevention of acute rheumatic fever. 1, 2, 3

Avoid cephalosporins in patients with immediate-type hypersensitivity to penicillin (anaphylaxis, angioedema, urticaria). 2, 3

Do not routinely retest asymptomatic patients after treatment completion as this leads to unnecessary retreatment of carriers. 2, 3 Post-treatment cultures are not indicated for asymptomatic patients. 3

Do not prescribe antibiotics for likely viral pharyngitis (patients with cough, rhinorrhea, hoarseness, oral ulcers). 3 Only treat culture-proven or rapid antigen test-proven GAS pharyngitis. 3

Ensure patients complete the full 10-day course as poor compliance is a major factor in treatment failure, with bacteriologic failure rates up to 35% when courses are not completed. 4, 5, 9, 10

Be aware that oral route should not be relied upon in patients with severe illness, nausea, vomiting, or intestinal hypermotility—use intramuscular benzathine penicillin G in these cases. 4, 5