What are the options for oral treatment of Group B Streptococcus (GBS)?

Oral Treatment Options for Group B Streptococcus (GBS)

For Group B Streptococcus infections, penicillin and amoxicillin are the first-line oral treatment options due to their proven efficacy, safety, narrow spectrum, and low cost. 1, 2

First-Line Oral Treatment Options

• Amoxicillin is the preferred oral treatment for GBS infections, particularly in children, with dosing of 50 mg/kg once daily (maximum 1000 mg) or 25 mg/kg twice daily (maximum 500 mg) for a standard 10-day course 1, 2
• Penicillin V is an effective alternative with dosing of 250 mg 2-3 times daily for children and 250 mg four times daily or 500 mg twice daily for adolescents and adults for a 10-day course 3, 2
• GBS has never shown resistance to penicillin, making these beta-lactam antibiotics highly reliable first-line options 1, 4
• For Group B streptococcal pharyngitis, the standard treatment duration is 10 days to ensure complete eradication and prevent complications 3, 2

Alternative Oral Options for Penicillin-Allergic Patients

• For patients with non-anaphylactic penicillin allergy, first-generation cephalosporins such as cephalexin or cefadroxil are recommended for a 10-day course 3, 1
• For patients with immediate hypersensitivity to penicillin, the following options are recommended:
  • Clindamycin (resistance rate approximately 1% in the US) 3, 1
  • Macrolides such as erythromycin or clarithromycin for a 10-day course 3, 1
  • Azithromycin for a 5-day course 3, 1
• Be aware that macrolide resistance rates among GBS isolates have been reported at around 30% in some regions, necessitating susceptibility testing when possible 5, 4

Special Considerations

• For neonatal GBS infections, studies have shown that after initial intravenous therapy, switching to oral amoxicillin (200-300 mg/kg/day in four divided doses) can maintain therapeutic levels in full-term neonates 6
• For pregnant women with GBS colonization, oral antibiotics are not recommended for eradication; instead, intrapartum antibiotic prophylaxis is the standard of care 7, 8
• For recurrent GBS pharyngitis, retreatment with the same agent used initially is recommended; if compliance is questionable, consider alternative approaches 2

Antibiotics to Avoid

• Tetracyclines should not be used due to high prevalence of resistant strains 3
• Sulfonamides and trimethoprim-sulfamethoxazole should be avoided as they do not effectively eradicate GBS 3
• Older fluoroquinolones (e.g., ciprofloxacin) have limited activity against GBS 3
• Newer fluoroquinolones (e.g., levofloxacin, moxifloxacin), while active against GBS, are not recommended due to their unnecessarily broad spectrum and high cost 3

Treatment Duration

• The standard treatment duration for GBS infections is 10 days for most oral antibiotics to achieve maximal pharyngeal eradication 3, 1
• While some newer antibiotics (cefdinir, cefpodoxime, azithromycin) have FDA approval for 5-day courses in GAS pharyngitis, these shorter regimens with broader-spectrum antibiotics are not fully endorsed for GBS due to higher cost and broader antimicrobial activity 3, 1

Common Pitfalls to Avoid

• Using broad-spectrum antibiotics like amoxicillin-clavulanate as first-line therapy unnecessarily increases costs and promotes antimicrobial resistance 1, 2
• Failing to complete the full 10-day course of antibiotics may lead to treatment failure and complications 3, 2
• Using macrolides without susceptibility testing in areas with high resistance rates can lead to treatment failure 5, 4
• Overlooking the possibility of penicillin allergy, which requires alternative antibiotic selection 3, 1