What is the recommended antibiotic prophylaxis for a pregnant patient with a penicillin allergy (hypersensitivity reaction) and ruptured membranes undergoing a cesarean section (C-section)?

Antibiotic Prophylaxis for Pregnant Patient with Penicillin Allergy Undergoing C-section

For a pregnant patient with penicillin allergy (including rash/hives) and ruptured membranes undergoing cesarean section, vancomycin 1g IV every 12 hours until delivery is the recommended antibiotic prophylaxis regimen.

Assessment of Penicillin Allergy

When evaluating a patient with reported penicillin allergy manifesting as a rash that could be hives:

• This history suggests a potential immediate hypersensitivity reaction (anaphylaxis, angioedema, or urticaria)
• According to CDC guidelines, patients with such reactions are considered at high risk for anaphylaxis 1
• These patients should not receive penicillin, ampicillin, or cephalosporins for prophylaxis

Antibiotic Selection Algorithm

For Ruptured Membranes (GBS Prophylaxis):

1. First determine allergy severity:

   • History of anaphylaxis, angioedema, respiratory distress, or urticaria (hives) = high risk
   • Your patient's rash that could be hives places her in this high-risk category

2. For high-risk penicillin allergy patients:

   • If GBS isolate susceptibility testing is available:
     • If susceptible to clindamycin: Clindamycin 900 mg IV every 8 hours until delivery
     • If resistant or unknown susceptibility: Vancomycin 1 g IV every 12 hours until delivery
   • If susceptibility testing is not available or results unknown:
     • Vancomycin 1 g IV every 12 hours until delivery 1

For C-section Prophylaxis:

• Standard regimen (non-allergic): Cefazolin 2g IV initial dose
• For penicillin-allergic patients: Clindamycin 900 mg IV + gentamicin 5 mg/kg/day 1

Integrated Approach for This Patient

Since this patient requires both GBS prophylaxis (for ruptured membranes) and C-section prophylaxis:

• Primary recommendation: Vancomycin 1 g IV every 12 hours until delivery
• Rationale: This covers both GBS prophylaxis needs and provides surgical prophylaxis
• Alternative if GBS susceptibility testing confirms clindamycin susceptibility: Clindamycin 900 mg IV every 8 hours until delivery

Important Clinical Considerations

• Azithromycin is not recommended in the CDC guidelines for GBS prophylaxis in penicillin-allergic patients 1
• Timing is critical - antibiotics should ideally be administered 15-60 minutes before skin incision for C-section 2
• Patients with penicillin allergies are at higher risk of not receiving timely prophylactic antibiotics before C-section 3
• The risk of surgical site infection increases significantly when appropriate antibiotics are delayed or omitted

Potential Pitfalls to Avoid

• Do not use cephalosporins in patients with history of potential immediate hypersensitivity reactions to penicillin (like this patient with possible hives)
• Do not delay antibiotic administration - research shows penicillin-allergic patients often experience delays in receiving prophylaxis 3
• Do not use clindamycin without susceptibility testing when possible, as resistance rates are increasing 1
• Do not extend prophylaxis beyond 24 hours as this does not provide additional benefit and may increase resistance 2

Documentation and Communication

• Clearly document the nature of the penicillin allergy in the medical record
• Ensure the surgical team is aware of both the allergy and the prophylaxis plan
• Consider penicillin allergy testing in the postpartum period for future pregnancies, as studies show 95% of patients with reported penicillin allergies can safely have this label removed 4