What is the first line treatment for group A streptococcal (GAS) infections?

First Line Treatment for Group A Streptococcal Infections

Penicillin V is the first line treatment for group A streptococcal (GAS) infections, administered at 250 mg four times daily or 500 mg twice daily for adults for 10 days. 1

Recommended Treatment Options

First Line Therapy

• Penicillin V (oral)
  • Adults: 250 mg four times daily or 500 mg twice daily for 10 days 1
  • Children: 250 mg three times daily (weight <27 kg) or appropriate weight-based dosing for 10 days 1

Alternative First Line Option

• Amoxicillin (oral)
  • Adults: 500 mg three times daily for 10 days 2
  • Children: 50 mg/kg once daily (maximum 1000 mg) or 25 mg/kg twice daily (maximum 500 mg per dose) for 10 days 1
  • Once-daily dosing (750 mg) has been shown to be as effective as penicillin V three times daily 3

Alternative Options for Penicillin-Allergic Patients

• Clindamycin (oral)

  • Adults: 300-450 mg three times daily for 10 days 1, 4
  • Children: 8-16 mg/kg/day divided into three or four equal doses 4

• Azithromycin (oral)

  • Adults: 500 mg once daily for 5 days 2, 1
  • Children: 12 mg/kg once daily (max 500 mg) for 5 days 1

Treatment Considerations

Duration of Therapy

• A full 10-day course is essential for penicillin and amoxicillin to prevent complications and ensure bacterial eradication 1, 5
• Studies have shown that 7-day penicillin courses have significantly higher failure rates (31%) compared to 10-day courses (18%) 5

Importance of Compliance

• Poor compliance is a major factor in treatment failure 6
• Once-daily amoxicillin may improve compliance compared to multiple daily doses of penicillin 3

Treatment Failure Management

If initial therapy fails:

1. Consider clindamycin 500 mg four times daily for 10 days 2
2. Alternative options include azithromycin 500 mg once daily for 5 days 2
3. For healthcare workers with persistent carriage, consider combination therapy with rifampicin or oral vancomycin 2

Special Considerations

Healthcare Workers with GAS

• Healthcare workers with symptomatic GAS infection should be excluded from work until 24 hours of appropriate treatment and resolution of symptoms 2
• For healthcare workers implicated in GAS transmission, eradication of carriage is recommended with appropriate antibiotics 2

Bacteriologic Failure Rates

• Penicillin failure rates have increased from 2-10% in the 1970s to approximately 30% in recent years 6
• Cephalosporins may produce higher clearance rates than penicillin but are not recommended as standard first-line therapy 2

Monitoring and Follow-up

• Cultures should be taken following completion of treatment to confirm eradication of streptococci 7
• In streptococcal infections, therapy must be sufficient to eliminate the organism (10-day minimum) to prevent sequelae of streptococcal disease 7

Potential Pitfalls

• Oral route should not be relied upon in patients with severe illness, nausea, vomiting, or intestinal hypermotility 7
• Prolonged antibiotic use may promote overgrowth of nonsusceptible organisms 7
• Skipping doses or not completing the full course increases the risk of treatment failure and antibiotic resistance 7

Remember that proper diagnosis should be established before initiating treatment, and a full 10-day course of therapy is essential for preventing complications of GAS infections, even if symptoms improve earlier.