Anaphylactic shock associated with cefuroxime axetil: Structure-activity relationships

Objective: To present a predictive model of allergenicity based on a structure-activity relationship analysis of P-lactam antibiotics using appropriate skin testing procedures. Case Summary: A 39-year-old woman was diagnosed with anaphylactic shock a few minutes after taking a 500 mg tablet cefuroxime of axetil and was admitted to the emergency department with dizziness, facial angioedema, generalized skin rash, and inferior cardiac ischemia. Skin testing confirmed the involvement of cefuroxime as the cause of the anaphylactic reaction, and the reaction was defined as probable according to the Naranjo probability scale. We then performed skin testing to study cross-reactivity between different, beta-lactam antibiotics. In addition to this initial assessment, a structure-activity relationship (SAR) analysis was done. It showed that the patient was sensitized to beta-lactam antibiotics presenting a methoxyimino group, but not to similar compounds lacking this chemical group (eg, amoxicillin or penicillin G or V). Challenge with amoxicillin under intensive medical monitoring was tolerated up to a cumulated dose of 1 g, administered intravenously over 2 hours. Discussion: This study demonstrates that SAR analysis could be useful to predict potential adverse reactions to related antibiotics and to select alternative strategies when antibiotic administration is essential. Conclusions: An SAR-based approach could help physicians and pharmacists provide allergic patients with relevant advice and propose viable alternatives regarding drug therapy.