Objective: To determine whether group B Streptococcus (GBS)-colonized pregnant women who report a history of penicillin allergy can safely undergo diagnostic evaluation to rule out or confirm the potential for an IgE-mediated (allergic) reaction to penicillin.

Methods: Over 18 months, all pregnant women with GBS-positive vaginal/rectal cultures and a history of penicillin allergy were referred to the Department of Allergy and Immunology for a history and possible skin testing. Patients who had experienced anaphylaxis were advised to continue avoiding penicillin and were not skin tested. Women without such a history underwent immediate hypersensitivity (percutaneous and intradermal) testing using 2 penicillin reagents with controls. If skin testing was negative, intrapartum antimicrobial prophylaxis with intravenous penicillin was administered.

Results: Of 28 patients with both GBS colonization and "penicillin allergy," 25 (89%) had negative skin testing to penicillin and received intrapartum penicillin for GBS prophylaxis without adverse reactions. Skin testing was positive in 2 patients, and intrapartum penicillin was not administered. Penicillin skin testing was not performed on 1 patient due to a history of anaphylaxis from penicillin.

Conclusions: These results indicate that most pregnant women reporting penicillin allergy undergo negative skin tests and are able to safely receive intrapartum penicillin GBS prophylaxis.