What is the recommended treatment for a patient with a group B strep (Streptococcus agalactiae) urinary tract infection (UTI) and a severe penicillin (PCN) allergy?

Treatment of Group B Strep UTI in Patients with Severe Penicillin Allergy

For patients with Group B Streptococcus (GBS) urinary tract infection and severe penicillin allergy, vancomycin is the recommended first-line treatment when susceptibility testing is not available or pending. 1

Defining Severe Penicillin Allergy

Severe penicillin allergy is characterized by:

• History of anaphylaxis following penicillin or cephalosporin administration 1
• Angioedema after penicillin or cephalosporin exposure 1
• Respiratory distress following penicillin or cephalosporin administration 1
• Urticaria after penicillin or cephalosporin exposure 1

Treatment Algorithm for GBS UTI with Severe Penicillin Allergy

First-line therapy:

• If susceptibility testing is not available or pending:

  • Vancomycin 1g IV every 12 hours until clinical improvement, then transition to appropriate oral therapy 1

• If susceptibility testing is available:

  • Susceptible to clindamycin and erythromycin:

    • Clindamycin 900 mg IV every 8 hours until clinical improvement, then transition to oral therapy 1

  • Resistant to erythromycin but susceptible to clindamycin with negative inducible resistance testing:

    • Clindamycin 900 mg IV every 8 hours 1

  • Resistant to clindamycin OR erythromycin-resistant with positive inducible clindamycin resistance:

    • Vancomycin 1g IV every 12 hours 1

Important considerations:

• GBS isolates should always undergo susceptibility testing for clindamycin and erythromycin in penicillin-allergic patients 1
• If an isolate is resistant to erythromycin, it might have inducible resistance to clindamycin, even if it appears susceptible to clindamycin on initial testing 1
• Testing for inducible clindamycin resistance (D-zone test) should be performed on erythromycin-resistant, clindamycin-susceptible isolates 1

Antimicrobial Resistance Patterns in GBS

• All GBS isolates remain susceptible to penicillin worldwide 1
• High rates of resistance to tetracyclines (96%) have been reported 2
• Macrolide (erythromycin) resistance is increasingly common (35% in some studies) 2
• Clindamycin resistance is also concerning (35% in some studies) 2
• All isolates remain susceptible to vancomycin 3, 2

Clinical Pearls and Pitfalls

• Do not use cefazolin in patients with severe penicillin allergy due to risk of cross-reactivity 1
• Do not use erythromycin for GBS infections as it is no longer recommended due to increasing resistance 1, 2
• Always obtain susceptibility testing when treating GBS infections in penicillin-allergic patients 1
• Ensure adequate hydration and monitor renal function when administering vancomycin 3
• Consider consultation with an infectious disease specialist for complicated cases or when limited treatment options are available 1
• For non-severe penicillin allergies (no history of anaphylaxis, angioedema, respiratory distress, or urticaria), cefazolin remains an acceptable alternative 1

Duration of Therapy

• For uncomplicated UTI: 7-10 days of appropriate antibiotic therapy 4
• For complicated UTI: 10-14 days of appropriate antibiotic therapy 4
• Consider longer duration in patients with structural abnormalities or immunocompromised status 4

By following this algorithm and considering the patient's specific allergy history and GBS susceptibility patterns, clinicians can effectively treat GBS UTI in patients with severe penicillin allergy while minimizing the risk of adverse reactions.