Treatment for Group B Streptococcus in Patients with Penicillin Allergy
For patients with Group B Streptococcus (GBS) infection and penicillin allergy, the recommended treatment depends on the severity of the allergy, with vancomycin being the first-line treatment for severe penicillin allergies when susceptibility testing is not available. 1
Assessment of Penicillin Allergy
- Determine if the patient has a high risk for anaphylaxis (severe penicillin allergy), characterized by history of anaphylaxis, angioedema, respiratory distress, or urticaria following penicillin or cephalosporin administration 1, 2
- Verification of reported penicillin allergy is important, as approximately 10% of persons with penicillin allergy have immediate hypersensitivity reactions to cephalosporins 2
Treatment Algorithm Based on Allergy Severity
For Non-Severe Penicillin Allergy:
- Cefazolin is the recommended alternative (2g IV initial dose, then 1g IV every 8 hours until treatment completion) 1, 2
- GBS isolates remain highly susceptible to cefazolin, with minimum inhibitory concentrations consistently low 2
For Severe Penicillin Allergy:
- Obtain antimicrobial susceptibility testing for clindamycin and erythromycin if possible 1, 2
- If the isolate is susceptible to clindamycin, administer clindamycin 900 mg IV every 8 hours 1, 2
- If susceptibility testing is not available or the isolate is resistant to clindamycin, administer vancomycin 1g IV every 12 hours 1, 2
Antimicrobial Resistance Considerations
- All GBS isolates remain susceptible to penicillin worldwide 1
- Erythromycin resistance has been increasing in GBS strains, with studies showing resistance rates of 12% in some populations 3
- Clindamycin resistance has also been reported, with rates of approximately 7% 3
- The CDC advises against using erythromycin for GBS infections due to increasing resistance 1
Clinical Pearls and Pitfalls
- Always obtain susceptibility testing when treating GBS infections in penicillin-allergic patients 1, 2
- Consider consultation with an infectious disease specialist for complicated cases or when limited treatment options are available 1
- Avoid cefazolin in patients with severe penicillin allergy due to risk of cross-reactivity 1
- Reserve vancomycin for cases where no other options exist, due to concerns about promoting antimicrobial resistance 2
- Antibiotic susceptibility testing should be performed on GBS isolates from penicillin-allergic patients, as this is an area for improvement in antibiotic stewardship 4
Special Considerations for Pregnant Patients
- For pregnant women with GBS colonization and penicillin allergy requiring intrapartum prophylaxis, follow the same principles based on allergy severity 4
- Cefazolin is most frequently used for non-severe allergies, followed by vancomycin and clindamycin for severe allergies 4
- Intrapartum exposure to penicillin for GBS treatment does not increase the risk of penicillin allergy in children 5