Study: Few delayed reactions to cephalosporins represent hypersensitivity

November 1, 2008

Nonimmediate reactions to cephalosporins are likely manifestations of the underlying infectious disease rather than mediated by IgE among kids.

An evaluation of 148 children with histories of hypersensitivity reactions to cephalosporins showed that whereas immediate reactions (within one hour) are immunoglobulin E (IgE)-mediated, nonimmediate reactions (after one hour) probably are manifestations of the underlying infectious disease rather than hypersensitivity reactions.

The children studied ranged in age from 2 to 14 years of age, and were patients in an allergy clinic. The cephalosporins that provoked reactions were mainly cefaclor and ceftriaxone; 105 children had nonimmediate manifestations of hypersensitivity (mostly urticarial eruptions and maculopapular rashes) and 43 immediate manifestations (anaphylactic shock, urticaria, or angioedema or erythema). Children with immediate manifestations underwent immediate-reading skin tests, serum-specific IgE assays and, if results were negative, challenges with the responsible cephalosporins. Children with nonimmediate manifestations were assessed with both patch tests and delayed-reading (at least 48 hours) skin tests and, if responses were negative, with challenges.

None of the children with nonimmediate reactions had positive responses to patch tests or delayed-reading skin tests. Of 96 patients with negative results who underwent challenges, 94 tolerated them with suspected cephalosporins. Another 43 tolerated other suspected drugs, such as penicillins and macrolides.

Commentary:

This study confirms what you already know: that all "allergic reactions" are not created equal. You can help define true IgE-mediated reactions with a careful history. Children with immediate symptoms are highly likely to be having a true IgE-mediated response, but those with delayed responses may deserve a more careful look before excluding future use of cephalosporins.

DR. BURKE, section editor for Journal Club, is chairman of the department of pediatrics at Saint Agnes Hospital, Baltimore. He is a contributing editor for Contemporary Pediatrics. He has nothing to disclose in regard to affiliations with, or financial interests in, any organization that may have an interest in any part of this article.