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