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CAP with Penicillin Allergy — RACP Adult Medicine MCQ

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HardInfectious DiseasesCAP with Penicillin AllergyRACP Adult Medicine

A 40-year-old woman with a known penicillin allergy (anaphylaxis) develops community-acquired pneumonia requiring hospital admission. She is haemodynamically stable with a SMART-COP score of 3. What is the most appropriate empirical antibiotic regimen?

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Correct answer: A — IV moxifloxacin

For moderate-severity CAP in patients with a history of penicillin anaphylaxis, cephalosporins have a cross-reactivity risk (though low with third-generation). According to eTG, respiratory fluoroquinolone (moxifloxacin) is an alternative for moderate-severe CAP with true penicillin anaphylaxis. However, eTG specifically notes moxifloxacin should be reserved for this indication given antimicrobial stewardship concerns. The actual eTG recommendation is to consider the risk/benefit of cephalosporin use given the very low cross-reactivity rate (<2%) with late-generation cephalosporins.

Reference: eTG – 2025 – Antibiotic Guidelines