Testing strategies and predictors for evaluating immediate and delayed reactions to cephalosporins

Stone, C.A., Trubiano, J.A. and Phillips, E.J. (2020) Testing strategies and predictors for evaluating immediate and delayed reactions to cephalosporins. The Journal of Allergy and Clinical Immunology: In Practice, 9 (1). 435-444.e13.

Abstract

Background
Although 1-2% of the general population carries a cephalosporin allergy label (CAL), we lack validated testing strategies and predictors of true allergy.

Objective
To identify cross-reactivity patterns and predictors of skin test positive (STP) in geographically disparate patients with a CAL.

Methods
780 adult patients labeled with a CAL or penicillin allergy label (PAL) with unknown tolerance of cephalosporins identified from the Austin Hospital (Melbourne Australia) (n=410) and Vanderbilt University Medical Center (Nashville, USA) (n=370) between 2014-2018, underwent a standardized skin testing.

Results
Of 328 patients with CAL, 29 (8.8%) tested STP to ≥ 1 cephalosporin(s). There were no cefazolin or ceftriaxone STP, 0/452 (0%), in patients with a PAL only. 16/328 (4.8%) patients with a CAL were ampicillin STP. 11/16 of these patients had an initial allergy label to cephalexin. 20/29 patients cephalosporin STP demonstrated tolerance to a cephalosporin with a different R1 side chain, and 8/14 ampicillin STP patients demonstrated tolerance of > 1 non-amino R1 group cephalosporin. 11/13 patients STP to cefazolin were skin and ingestion challenge negative to all other penicillins and cephalosporins predicted by its distinct R1/ R2 groups. 7/15 ceftriaxone STP patients demonstrated cross-reactivity with R1-similar cephalosporins. Time since original reaction predicted STP testing to both penicillins, aOR (adjusted odds ratio) per year 0.93 (95% CI 0.90, 0.97), and cephalosporins aOR per year 0.71 (95%CI 0.56, 0.90).

Conclusions
Cephalosporin cross-reactivity is based on shared R1 groupings. Increasing time since original reaction, and the presence of a PAL with unknown cephalosporin tolerance predict a lower likelihood of cephalosporin STP.

Item Type:	Journal Article
Murdoch Affiliation(s):	Institute for Immunology and Infectious Diseases
Publisher:	Elsevier
Copyright:	© 2020 Published by Elsevier Inc. on behalf of the American Academy of Allergy, Asthma & Immunology
URI:	http://researchrepository.murdoch.edu.au/id/eprint/57347

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