Diagnostic Approach of Hypersensitivity Reactions to Cefazolin in a Large Prospective Cohort.

Abstract

Introduction: Cefazolin is a common trigger of perioperative anaphylaxis. The diagnostic approach is controversial as the optimal concentration for skin testing is uncertain, drug provocation tests (DPTs) are contraindicated in severe reactions, and in vitro tests are not thoroughly validated. We aimed to characterise a large number of patients reporting cefazolin allergic reactions, and to analyse in vivo and in vitro tests’ diagnostic role. Methods: We prospectively evaluated patients with suspicion of allergic reactions to cefazolin by clinical history, skin tests (STs), and, if negative, DPT. In a subgroup of patients (both allergic and non-allergic), basophil activation test (BAT) and radioallergosorbent test (RAST) were also done. Results: From 184 evaluated patients, 41.3% were confirmed as allergic, 48.9% as non-allergic, and in 9.8% diagnosis was not confirmed. All reactions were immediate, besides, all cases reporting anaphylactic shock and most patients reporting anaphylaxis were confirmed as allergic (p<0.001); 52.6% of allergic cases were confirmed by STs, 28.9% by DPT, and 18.4% by clinical history. All subjects manifesting exanthemas and generalised pruritus were non-allergic. BAT sensitivity was 66.7% when combining CD63 and CD203c as activation markers. Six out of eight patients with negative STs and positive DPT had a positive BAT. Conclusions: Allergic patients to cefazolin often reported severe immediate-type reactions. STs allowed diagnosing half of patients. Unfortunately, DPT could not be performed in all cases due to reaction severity, being BAT a promising diagnostic tool. Further researches are needed to clarify the underlying mechanisms, especially in patients with severe reactions.