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

Defining Severe Penicillin Allergy

Severe penicillin allergy is characterized by a history of anaphylaxis following penicillin or cephalosporin administration, angioedema after penicillin or cephalosporin exposure, respiratory distress following penicillin or cephalosporin administration, or urticaria after penicillin or cephalosporin exposure, as defined by the Centers for Disease Control and Prevention (CDC) 1

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, according to the CDC 2, 3, 4
If susceptibility testing is available, the CDC recommends clindamycin 900 mg IV every 8 hours for susceptible isolates, or vancomycin 1g IV every 12 hours for resistant isolates 2, 4, 5
The CDC advises against using cefazolin in patients with severe penicillin allergy due to risk of cross-reactivity 1
The CDC also recommends against using erythromycin for GBS infections as it is no longer recommended due to increasing resistance 5

All GBS isolates remain susceptible to penicillin worldwide, according to the Infectious Diseases Society of America (IDSA) 6

The CDC recommends always obtaining susceptibility testing when treating GBS infections in penicillin-allergic patients 5
The CDC suggests considering consultation with an infectious disease specialist for complicated cases or when limited treatment options are available 5
For non-severe penicillin allergies, the CDC recommends cefazolin as an acceptable alternative 1

For patients without severe reactions, cefazolin is the recommended alternative, as true penicillin allergy occurs in a smaller percentage of patients than reported, according to the MMWR Recommendations and Reports 7, 8
Verification of allergy history is important before selecting alternative antibiotics, as cross-reactivity between penicillins and cephalosporins occurs in approximately 10% of patients with penicillin allergy, as stated by the MMWR Recommendations and Reports 8

GBS isolates remain highly susceptible to cefazolin, as reported by the MMWR Recommendations and Reports 8

Obtain antimicrobial susceptibility testing for clindamycin and erythromycin if possible, according to the MMWR Recommendations and Reports 7

The Centers for Disease Control and Prevention (CDC) recommends performing D-zone testing on isolates that are erythromycin-resistant but clindamycin-susceptible to detect inducible clindamycin resistance, as resistance to erythromycin is frequently but not always associated with clindamycin resistance 9

The CDC reports that clindamycin resistance ranges from 3-15% among invasive GBS isolates, highlighting the need for susceptibility testing 9
According to the CDC, all GBS isolates worldwide remain susceptible to penicillin, with no confirmed resistance to penicillin or ampicillin observed to date 9, 10