What can be used to treat Group B strep (GBS) vaginal infection in patients allergic to penicillin (PCN)?

Treatment of Group B Strep Vaginal Infection in Penicillin-Allergic Patients

For patients with vaginal Group B Streptococcus (GBS) infection who are allergic to penicillin, cefazolin is the recommended first-line treatment unless the patient has a history of anaphylaxis to penicillin. 1, 2

Treatment Algorithm Based on Penicillin Allergy Severity

Low Risk for Anaphylaxis

• First-line: Cefazolin 2g IV initial dose, then 1g IV every 8 hours until delivery 1, 2
• This is recommended for patients without history of immediate hypersensitivity reactions to penicillin (anaphylaxis, angioedema, respiratory distress, or urticaria)

High Risk for Anaphylaxis

For patients with history of anaphylaxis, angioedema, respiratory distress, or urticaria following penicillin administration:

1. If GBS isolate is tested and susceptible:

   • Clindamycin 900mg IV every 8 hours until delivery 1, 2

2. If susceptibility testing is unavailable OR isolate is resistant to clindamycin/erythromycin:

   • Vancomycin 1g IV every 12 hours until delivery 1

Important Considerations

Susceptibility Testing

• Antimicrobial susceptibility testing should be ordered for all GBS cultures from penicillin-allergic women at high risk for anaphylaxis 1, 2
• Recent studies show increasing resistance to clindamycin (8.2-28%) and erythromycin (9.6-30%) 3, 4, 5
• Multiple studies have demonstrated that resistance rates to these antibiotics are rising, making susceptibility testing crucial 3, 6

Resistance Patterns

• The rate of co-resistance to clindamycin among erythromycin-resistant strains can be as high as 92% 3
• Serotype V GBS has been associated with higher erythromycin resistance 4
• All GBS isolates remain susceptible to penicillin and vancomycin 3, 7, 4

Ineffective Treatments

• Oral antibiotics during pregnancy are not effective for eliminating GBS colonization or preventing neonatal disease 1, 2
• Erythromycin is no longer recommended for GBS prophylaxis due to increasing resistance and poor placental transfer 2

Special Populations

• Patients from Asia may show higher proportions of erythromycin and clindamycin resistance 4
• For pregnant women, these recommendations apply to intrapartum prophylaxis to prevent neonatal GBS disease
• For non-pregnant women with vaginal GBS infection, the same antibiotic choices apply, though route and duration may differ

Monitoring

• For patients receiving vancomycin, monitor for potential side effects including:
  • Nephrotoxicity, especially in patients >65 years of age 8
  • Ototoxicity in patients with kidney dysfunction or preexisting hearing loss 8
  • "Red Man Syndrome" (hypotension, wheezing, flushing of upper body) 8

By following this evidence-based approach to treating GBS vaginal infection in penicillin-allergic patients, clinicians can provide effective therapy while minimizing risks associated with antibiotic resistance and adverse reactions.