Evaluation of Cross-Reactivity Between Penicillins and Cephalosporins in Children with a History of Cephalosporin Allergy.

Objectives: The cross-reactivity problem between cephalosporins and penicillins has mainly been evaluated in the context of patients allergic to penicillins. However, we have little data regarding the opposite aspect of the problem, i.e. the cross-reactivity in subjects primarily sensitized to cephalosporins. This prospective study aims to evaluate the cross-reactivity to penicillins and some other cephalosporins in patients with immediate allergic reactions to cephalosporins.

Methods: The study included 21 children with immediate allergic reactions to at least one cephalosporin. Skin testing was performed with a panel of minor and major determinant mixtures of penicillins and three commonly used cephalosporins (cephazoline, cefuroxime and ceftriaxone).

Results: The children had used 5.14±4.91 (1-15) times any beta-lactam antibiotic in the previous year and the most common cephalosporins accused were ceftriaxone (42.92%), and cefuroxime, cefazolin, cefixime, cefprozil and cefotaxime (9.5% each). Skin tests were positive for any cephalosporin in 14 (66.7%) subjects and penicillin allergens in 15 (71.4%) subjects. Totally, 85.7% of children with a positive allergy history to cephalosporins were found to be sensitive to either penicillin or any one of three cephalosporins.

Conclusion: There seems to be a high risk of adverse reactions to penicillins and other cephalosporins in children with a history of type I hypersensitivity reaction to cephalosporins. Therefore, skin testing with both cephalosporins and penicillins should be performed in patients with a history of cephalosporin allergy.