GIM Question 30 Instructor

A patient on your ward develops a red, hot, painful, well-defined rash on his right lower leg. You notice he has a temperature of 390C.

  1. What is your differential diagnosis?
    The differential diagnosis for this patient includes:

    • Cellulitis (most likely)
    • Erysipelas
    • Venous stasis dermatitis (bilateral, progressive, history of venous stasis dermatitis)
    • Deep vein thrombosis (recent immobilization, orthopaedic surgery, malignancy, history of DVT)
    • Necrotizing fasciitis (crepitus +/- pain out of proportion)
    • Gout, septic arthritis (focused on a joint)
    • Adverse drug reaction (known drug allergy, diffuse rash, onset after drug administration)
    • Malignancy (weight loss, progressive)
  2. You suspect he has cellulitis. What are the common pathogens underlying this condition?
    Common pathogens for cellulitis involve gram positive organisms typically found on the skin: Group A Streptococcus, Staphylococcus aureus (especially if purulent lesion).
  3. What is your initial treatment?
    Empiric antibiotics typically involve cephalexin/cefazolin for the common pathogens:

    • Cephalexin 500mg PO qid for 5-7days
    • Cefazolin 1-2g IV q8h for 5-7days (if unable to tolerate PO)

    If penicillin allergic:

    • Clindamycin 450mg PO qid (or 600mg IV TID)
    • Moxifloxacin 400mg PO daily or levofloxacin 500mg PO daily
    • Linezolid 600mg PO BID (usually needs infectious disease approval)
    • Vancomycin 1g IV q12h

    In diabetic patients there is a concern for polymicrobial infections, and therefore consideration should be given for starting ciprofloxacin and clindamycin.

Swartz MN. Clinical practice. Cellulitis. N Engl J Med. 2004, 350:904-912.

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