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Cellulitis/Erysipelas — RACP Adult Medicine MCQ

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EasyInfectious DiseasesCellulitis/ErysipelasRACP Adult Medicine

A 45-year-old woman presents with a painful, red, hot lower leg. There is a well-demarcated, raised, erythematous plaque on the medial shin. She has a temperature of 39°C and WCC of 18 × 10⁹/L. She has no penicillin allergy. What is the most appropriate antibiotic?

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Correct answer: C — Vancomycin IV

Well-demarcated, raised erythema with systemic symptoms suggests erysipelas (superficial cellulitis typically caused by group A Streptococcus). For severe erysipelas requiring IV antibiotics, eTG recommends benzylpenicillin (or flucloxacillin if staphylococcal co-infection is suspected). Flucloxacillin is appropriate as it covers both streptococcal and staphylococcal infections. For mild cellulitis in penicillin-non-allergic patients, oral flucloxacillin or cefalexin is used.

Reference: eTG – 2025 – Antibiotic Guidelines