Penicillin allergies and selection of intrapartum antibiotic prophylaxis against group B Streptococcus at a safety-net institution.

Objective: To evaluate the rate of documented penicillin allergies in obstetric patients and to estimate the proportion of patients receiving inappropriate alternative intrapartum Group B Streptococcus (GBS) prophylaxis.

Methods: This was a retrospective cohort study of patients delivering at Denver Health Medical Center (DHMC) between April 27, 2017 and October 31, 2022. The study included all patients with documented penicillin allergy and GBS positive status during routine prenatal care. Records were reviewed for allergy severity/risk and antibiotic administered for GBS prophylaxis. Allergy severity/risk was based on whether there was a documented reaction in the electronic health record and the presence or absence of anaphylaxis, angioedema, respiratory distress, or urticaria. Patients were classified as receiving appropriate or inappropriate intrapartum antibiotic prophylaxis based on their allergy risk stratification and whether they received standard (e.g. penicillin, cefazolin) or alternative (e.g. clindamycin, vancomycin) antibiotics. The primary outcome was inappropriate prophylaxis, defined as receiving an alternative antibiotic in the setting of a low-risk penicillin allergy. Secondary maternal and neonatal outcomes were abstracted and compared based on appropriateness of antibiotic selection.

Results: There were 18,931 unique patient encounters during the study period, of whom 1,262 (6.7 %) had a documented penicillin allergy. Of patients with penicillin allergies, 196 were GBS-colonized. Of the 86 GBS-colonized patients with low-risk penicillin allergies, 54 (62.8 %) received inappropriate antibiotic prophylaxis (i.e. received alternative antibiotics despite a low-risk allergy). Fewer than 7 % of pregnant patients developed complications, including chorioamnionitis, endometritis, or surgical site infection within 30 days. Only one neonate was diagnosed with GBS bacteremia.

Conclusions: More than half of GBS-colonized patients with low-risk penicillin allergies at our institution received inappropriate intrapartum antibiotic prophylaxis. These data support the need for improved documentation of allergy type and severity and antibiotic selection to expand adherence to guideline recommendations.