What is the treatment for Group C streptococcal (Strep C) infections?

Treatment for Group C Streptococcal Infections

Penicillin is the first-line treatment for Group C streptococcal infections, administered for 10 days to achieve maximal pharyngeal eradication. 1

First-Line Treatment Options

For patients without penicillin allergy:

• Penicillin V (oral):

  • 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
  • Note: The twice-daily regimen has shown similar efficacy to three-times-daily dosing 3

• Amoxicillin (oral):

  • 50 mg per kg once daily (maximum = 1,000 mg) for 10 days 2
  • Alternative: 25 mg per kg twice daily (maximum = 500 mg) for 10 days 2

• Penicillin G benzathine (intramuscular):

  • < 60 lb (27 kg): 600,000 U as a single dose 2
  • ≥ 60 lb: 1,200,000 U as a single dose 2
  • Preferred for patients unlikely to complete a full 10-day course of oral therapy 2

Treatment for Penicillin-Allergic Patients

For patients with penicillin allergy:

• Cephalexin (Keflex) (oral):

  • 20 mg per kg per dose twice daily (maximum = 500 mg per dose) for 10 days 2
  • Avoid in individuals with immediate hypersensitivity to penicillin 2

• Cefadroxil (oral):

  • 30 mg per kg once daily (maximum = 1 g) for 10 days 2
  • Avoid in individuals with immediate hypersensitivity to penicillin 2

• Clindamycin (oral):

  • 7 mg per kg per dose three times daily (maximum = 300 mg per dose) for 10 days 2, 4
  • For severe penicillin allergy, this is a preferred option 5

• Azithromycin (Zithromax) (oral):

  • 12 mg per kg once daily (maximum = 500 mg) for 5 days 2
  • Note: Resistance of Group C streptococcus to macrolides is well-known and varies geographically 2

• Clarithromycin (Biaxin) (oral):

  • 7.5 mg per kg per dose twice daily (maximum = 250 mg per dose) for 10 days 2
  • Note: Resistance concerns similar to azithromycin 2

Treatment Duration Considerations

• Most oral antibiotics must be administered for a full 10-day course to achieve maximal pharyngeal eradication of streptococci 2
• Azithromycin is an exception, requiring only a 5-day course due to its prolonged tissue half-life 5
• Shorter duration therapies (3-6 days) with newer antibiotics have been studied but are not universally recommended, particularly in areas with high rates of rheumatic heart disease 6

Management of Treatment Failures and Carriers

For patients with recurrent Group C streptococcal pharyngitis or chronic carriers:

• Clindamycin (oral):

  • 20 to 30 mg per kg per day in three doses (maximum = 300 mg per dose) for 10 days 2
  • Highly effective for eradicating streptococci in chronic carriers 5

• Penicillin and rifampin combination (oral):

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

• Amoxicillin/clavulanate (Augmentin) (oral):

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

Adjunctive Therapy

• Analgesics or antipyretics (e.g., acetaminophen, NSAIDs) can be considered for moderate to severe symptoms or high fever 2
• Aspirin should be avoided in children due to risk of Reye syndrome 2
• Corticosteroids are not recommended as adjunctive therapy 5

Important Clinical Considerations

• Treatment failure with penicillin has increased over time, from 2-10% in the 1970s to approximately 30% in recent years 7
• Causes of treatment failure include poor compliance, reexposure to infected individuals, copathogenicity, and penicillin tolerance 7
• Group C streptococci, particularly Streptococcus dysgalactiae subsp. equisimilis (SDSE), can cause a range of infections from mild to life-threatening, similar to Group A streptococci 1
• Follow-up post-treatment testing is not routinely recommended but may be considered in special circumstances 2
• Testing of asymptomatic household contacts is not routinely recommended unless there are specific indications 2