OSCE — antimicrobials for skin infection: cellulitis vs abscess, stewardship, and when to escalate

Brief (to candidate)

A 45-year-old has an acutely red, hot, painful lower leg with fever. There is no fluctuance. A second patient has a tender pointing boil with central pustule. You have 8 minutes to diagnose, decide antibiotics versus drainage, and apply stewardship and safety-netting.

Candidate instructions

1. Differentiate cellulitis/erysipelas, abscess/furuncle, and mimics (stasis dermatitis, DVT, contact dermatitis).
2. Choose empiric oral vs IV pathway using severity.
3. State when incision and drainage is primary therapy.
4. Apply antibiotic stewardship (duration, avoid unnecessary broad agents).
5. Identify necrotising infection red flags.

Examiner checklist (mark each domain / 10)

Model key actions

• Treat non-purulent cellulitis with appropriately targeted antibiotics and severity-based route.^[1][2]
• Drain abscesses; do not rely on antibiotics alone when pus is present.^[3]
• Exclude necrotising infection and common non-infectious mimics.^[5]

Common errors

• Antibiotics alone for drainable abscess.
• Treating bilateral chronic stasis dermatitis as recurrent cellulitis for months.
• Missing necrotising fasciitis red flags.
• Endless broad-spectrum therapy without reassessment.
• Ignoring portal of entry (tinea, ulcer).