A *Corresponding Author. E-Mail: Parkhk@Puan.Ac.Kr **Corresponding Author. , Email: Helenmed@Snu.Ac.Kr

Background: Beta-lactams (BLs) are commonly used antibiotics and leading causative agents of drug-induced anaphylaxis. Few studies on the culprit drugs and risk factors of BL-induced anaphylaxis are available. Our goal was to evaluate the culprit drugs and compare the risk fac-tors in patients with BL-induced anaphylaxis to matched tolerant controls in a hospital setting. Methods: We retrospectively enrolled all patients who developed anaphylaxis from intravenous BL during hospitalization from 9 Korean hospitals. We compared clinical parameters between patients with BL-induced anaphylaxis and 4-fold BL-tolerant controls matched by age, sex, BL use, and the purpose of BL administration. Results: Seventy-four cases of BL-induced anaphylaxis and 296 BL-tolerant controls were enrolled. Cephalosporin accounted for 77% of total BL-induced anaphylaxis, and the top de-rivatives were ceftriaxone (23.0%), cefazedone (10.8%), and cefbuperazone (9.5%). Among penicillin derivatives, piperacillin (16.2%) was the most common, followed by ampicillin (2.7%). History of drug allergy (odds ratio [OR], 19.91; 95% confidence interval [CI] 5.33-74.44), previous exposure to the causative BL (OR, 7.71; 95% CI, 1.62-36.76), and concurrent administration of angiotensin-converting enzyme inhibitors (ACEIs) (OR, 5.97; 95% CI, 1.28-27.91) were indepen-dent risk factors associated with BL-induced anaphylaxis. Food allergy (OR, 13.93; 95% CI 1.31- 148.9) and previous exposure to BL (OR, 6.59; 95% CI, 1.30-33.31) were identified as risk factors for cephalosporin-induced anaphylaxis. Conclusions: To prevent BL-induced anaphylaxis, attention should be paid to histories of drug or food allergy, previous exposure to BLs, and ACEI use. The risk factors and clinical outcomes might vary according to the BL classes.