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How to diagnose allergy to cefazolin, a perioperative antibiotic

Published August 28, 2021

Cefazolin is the most common antibiotic inducing allergic reactions in perioperative settings. Its clinical symptoms are usually severe, such as anaphylaxis, which is a life-threatening allergic reaction. The correct diagnosis is critical to prevent recurrence and to avoid alternative medications. The diagnostic approach is primarily based on clinical history and in vivo tests including skin tests (STs) and controlled administration of the drug in the clinical setting (drug provocation tests, DPTs). However, they have limitations as the value of STs is uncertain and DPT can re-induce the reaction, so it can be risky. A safer alternative can be in vitro tests, which only require blood sample extraction. However, these tests are not commercially available yet and those used for research purposes have not been still validated.

In a recent study published in The Journal of Allergy and Clinical Immunology: In Practice, Bogas and Doña et al have studied the role of in vivo and in vitro tests in reaching an accurate diagnosis. With this aim, a large group of patients with unequivocal suspicion of allergic reactions to cefazolin have been clinically characterized in detail. Furthermore, analysis of results obtained from in vivo (ST and DPT) and in vitro test (basophil activation test (BAT) and specific antibody (IgE) determination by immunoassay) was also performed.

The authors evaluated 184 patients with suspicion of allergic reactions to cefazolin. They found that almost half of them were allergic to this drug. In addition, most of them developed severe reactions like anaphylactic shock in less than one hour after drug administration. Nearly half of the remaining patients, who manifested less severe symptoms such as exanthema and pruritus, were finally confirmed as non-allergic to cefazolin, but allergic to other perioperative drugs. Within the allergic-patients group, half of them were confirmed by STs using cefazolin at 20mg/mL dilution, and one-third by DPT. In a subgroup of patients, BAT and immunoassay efficacy was evaluated, with BAT showing the best results. Moreover, BAT was able to detect 66% of allergic patients. Importantly, BAT could diagnose patients with negative results in ST; thus BAT is a promising diagnostic tool especially in patients who cannot undergo DPT due to the severity of the reaction.  

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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