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Ceftriaxone Penicillin Allergy Meningitis — SCE Infectious Diseases MCQ

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EasyCNS InfectionCeftriaxone Penicillin Allergy MeningitisSCE Infectious Diseases

A 60-year-old man develops acute community-acquired meningitis. He has a penicillin allergy documented as 'childhood rash.' He was given IV Ceftriaxone and Dexamethasone. Is Ceftriaxone appropriate given his penicillin allergy?

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Correct answer: E — Yes — the cross-reactivity between penicillins and 3rd-generation cephalosporins is very low (<2%); a vague childhood rash is very unlikely to represent true allergy; Ceftriaxone is appropriate for meningitis

Cross-reactivity between penicillins and 3rd-generation cephalosporins is very low (<2%). A vague 'childhood rash' history is overwhelmingly likely to represent a non-allergic reaction (viral exanthem, aminopenicillin rash with concurrent EBV). In life-threatening meningitis, the benefit of Ceftriaxone far outweighs the minimal cross-reactivity risk. True penicillin anaphylaxis warrants greater caution — Chloramphenicol or Meropenem (cross-reactivity <1%) are alternatives. Structured penicillin allergy assessment should be performed after the acute illness to clarify allergy status.

Reference: NICE CG102 2010 – Meningitis; BSACI 2024 – Penicillin allergy; BNF 2024