Screening for penicillin allergy in obstetric patients to optimize guideline directed therapy.

Objective: To assess the safety of penicillin allergy evaluation and testing in obstetric patients utilizing oral drug challenges with or without prior penicillin skin testing (PST) depending on characteristics of the patient's medication reaction, and to determine whether removal of the drug allergy label led to an increased use of guideline-recommended antibiotic prophylaxis for group B Streptococcus (GBS).

Design and setting: This retrospective cohort study evaluated obstetric patients cared for at the University of Iowa Health Care who were identified as having a penicillin allergy label between June 1, 2021 and July 1, 2023.

Patients: A total of 728 patients were identified to have a penicillin allergy and 299 patients were seen in the drug allergy clinic (DAC) for allergy evaluation.

Results: Of patients seen in the DAC for allergy evaluation, 270 (90.3%) had their allergy de-labeled after undergoing an oral drug challenge with or without PST. No patients experienced an IgE-mediated anaphylactic reaction to an oral drug challenge. Patients received penicillin G more often for GBS prophylaxis during labor when they had their drug allergy removed in the DAC compared to those who were not seen for allergy evaluation (87.5% vs 24.5%, P < 0.001).

Conclusions: This study supports the safety of drug allergy testing in obstetric patients. Most patients are appropriate candidates for a direct oral challenge only or PST followed by an oral challenge. Identifying and testing penicillin allergic obstetric patients prior to delivery resulted in an increase in use of first-line guideline-recommended antibiotic prophylaxis for GBS during labor.