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Beta-Lactam Cross-Reactivity — SCE Infectious Diseases MCQ

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ModerateAntimicrobial StewardshipBeta-Lactam Cross-ReactivitySCE Infectious Diseases

A hospital antibiotic pharmacist receives a query about whether Meropenem can be used for a patient with a documented cephalosporin allergy (anaphylaxis to Cefuroxime). What is the evidence regarding cross-reactivity?

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Correct answer: B — Cross-reactivity between cephalosporins and carbapenems is extremely low (<1%); Meropenem can generally be used safely even with cephalosporin anaphylaxis

Cross-reactivity between cephalosporins and carbapenems is extremely low (<1%) based on large retrospective studies and meta-analyses. Meropenem can generally be used safely in patients with cephalosporin allergy, including those with history of anaphylaxis, though administration under supervision (in a monitored setting for the first dose) is prudent. The structural dissimilarity between cephalosporin and carbapenem side chains explains the low cross-reactivity. Allergist referral for skin testing may be considered in unclear cases.

Reference: BSACI 2024 – Drug allergy guidelines; NICE CKS 2024 – Penicillin allergy