Zero confirmed allergic reactions to cefazolin in an elective orthopedic cohort with high prevalence of reported beta-lactam allergies.

Background: Cefazolin is the most effective prophylactic antibiotic for orthopedic surgeries. There is a high prevalence of patient-reported beta-lactam antibiotic allergies, which often results in inferior pre-operative antibiotics use. This study's purpose was to determine the rate of true allergic reactions among patients with a reported beta-lactam allergy when administered cefazolin. The hypothesis was that the rate of true allergic reactions would be low following cefazolin administration among patients with reported beta-lactam allergy. Methods: Patients undergoing orthopedic surgical procedures by a single surgeon between January 2023 and December 2024 were included. Reported autoimmune/psychiatric disorders, total number of reported allergies, type of reported beta-lactam antibiotic allergy, reported symptoms to beta-lactam antibiotic, and reported allergy severity were obtained via electronic medical records. Allergies were categorized as "true allergies" (anaphylactic/non-anaphylactic) or "other reactions." Demographic and allergy characteristics were compared between patients who did and did not report a beta-lactam antibiotic allergy. Results: Of 1,603 patients (57 ± 18 years; 47% female), 310 (19%) patients reported a beta-lactam antibiotic allergy and 230/310 (74%) specifically reported a penicillin allergy. Female (61% vs. 44%, Conclusion: Zero patients with a reported beta-lactam antibiotic allergy were found to have a true allergic reaction during the intraoperative or immediate post-operative period following cefazolin administration during an orthopedic surgery. Although reported allergies should be critically evaluated, this suggests cefazolin may be safely administered even if a beta-lactam antibiotic allergy is reported.