What are the treatment options for strep A (Streptococcus A) infections?

Treatment Options for Strep A Infections

Penicillin V remains the first-line treatment for strep A infections due to its proven efficacy, safety, narrow spectrum, and low cost. 1

First-Line Treatment Options

For Patients Without Penicillin Allergy:

1. Oral Penicillin V

   • Children: 250 mg two or three times daily for 10 days 2
   • Adolescents and adults: 250 mg four times daily or 500 mg twice daily for 10 days 2

2. Oral Amoxicillin (often used in place of penicillin V in young children due to better taste acceptance)

   • 50 mg/kg once daily (maximum 1,000 mg) or 25 mg/kg twice daily (maximum 500 mg) for 10 days 2, 1

3. Intramuscular Benzathine Penicillin G (for patients unlikely to complete oral therapy)

   • <60 lb (27 kg): 600,000 units as a single dose
   • ≥60 lb (27 kg): 1,200,000 units as a single dose 2, 1

For Patients With Penicillin Allergy:

1. Cephalosporins (avoid in patients with immediate hypersensitivity to penicillin)

   • Cephalexin: 20 mg/kg twice daily (maximum 500 mg per dose) for 10 days 2
   • Cefadroxil: 30 mg/kg once daily (maximum 1 g) for 10 days 2

2. Clindamycin

   • 7 mg/kg three times daily (maximum 300 mg per dose) for 10 days 2, 1

3. Macrolides (note: resistance is well-known and varies geographically)

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

Important Clinical Considerations

1. Treatment Duration

   • A full 10-day course is essential for most antibiotics to ensure eradication and prevent complications, particularly rheumatic fever 1, 3
   • Exceptions with FDA approval for shorter courses include azithromycin (5 days) 1, 4

2. Treatment Failure Considerations

   • Penicillin failure rates have increased from 2-10% in the 1970s to approximately 30% more recently 5
   • Primary causes include poor compliance with the 10-day regimen, reexposure to infected individuals, and penicillin tolerance 5
   • If symptoms persist or worsen after 5 days of appropriate treatment, consider:
     • Non-compliance with the prescribed regimen
     • Treatment failure
     • New infection
     • Viral pharyngitis in a streptococcal carrier 1

3. Macrolide Resistance

   • Resistance to macrolides is significant in some regions 1, 4
   • Susceptibility testing should be performed when using azithromycin 4
   • Macrolides should only be used in truly penicillin-allergic patients 1

4. Patient Management

   • Patients are considered non-contagious after 24 hours of antibiotic therapy 1
   • Symptoms typically improve within 24-48 hours after starting treatment 1
   • Acetaminophen or ibuprofen can be used for pain and fever control (avoid aspirin in children due to risk of Reye syndrome) 1

Treatment for Chronic Carriers

For patients identified as chronic carriers of Group A Streptococcus:

1. Clindamycin (oral)

   • 20-30 mg/kg/day in three doses (maximum 300 mg per dose) for 10 days 2

2. Penicillin and Rifampin (oral)

   • Penicillin V: 50 mg/kg/day in four doses for 10 days (maximum 2,000 mg/day)
   • Rifampin: 20 mg/kg/day in one dose for last four days of treatment (maximum 600 mg/day) 2

3. Amoxicillin/Clavulanate (oral)

   • 40 mg amoxicillin/kg/day in three doses (maximum 2,000 mg amoxicillin/day) for 10 days 2

Follow-up Recommendations

• Routine post-treatment throat cultures or rapid antigen detection tests are not recommended 1
• Testing or treatment of asymptomatic household contacts is not routinely recommended 1
• Full course completion is essential even if symptoms resolve quickly 1, 3

Pitfalls to Avoid

1. Incomplete Treatment Course

   • Skipping doses or not completing the full course may decrease treatment effectiveness and increase antibiotic resistance 3

2. Inappropriate Antibiotic Selection

   • Using macrolides in areas with high resistance without susceptibility testing 1, 4
   • Using sulfonamides or tetracyclines (not recommended due to higher resistance rates) 2

3. Inadequate Duration

   • Shorter courses than recommended may not eradicate the organism and can lead to complications 1, 3

4. Overlooking Penicillin Absorption Issues

   • The oral route should not be relied upon in patients with severe illness, nausea, vomiting, or intestinal motility disorders 3