Cellulitis - Diagnosis and Management Summary
Clinical Features: erythema, warmth, tenderness, edema, induration +/- purulence; smooth, poorly demarcated (vs. erysipelas-well demarcated). May have lymphangitis, LAD, vesicles/bullae, fever (20-77%), leukocytosis (34-50%)
Risk factors: venous stasis, lymphedema, PVD, DM, obesity, IVDU, tinea pedis, ulcer, trauma/ bite, eczema, XRT
Differential Diagnosis: (NB: if “bilateral cellulitis,” strongly consider alternative diagnosis)
• Non-infectious: stasis/contact dermatitis, drug rxn, DVT, eosinophilic cellulitis, lymphedema, vasculitis, gout
• Infectious: abscess, nec fasciitis/gas gangrene, bursitis, osteo, zoster, erythema migrans
Diagnosis: Clinical. Can use ALT-70 score (shown to reduce abx use)
• Blood & wound cultures not recommended for typical cellulitis. Obtain if: evidence of systemic toxicity, extensive skin involvement, immunosuppression, special exposures (bites, water), recurrent/persistent cellulitis.
• Consider ultrasound to assess for presence of abscess
• Purulent (abscess or fluctuance): MRSA (67%) > MSSA (17%) > Strep (5%)
• Non-purulent: Strep >> S. aureus > aerobic GNRs
• Specific associations: gas gangrene (myonecrosis) → C. perfringens; dog/cat bite → Capnocytophaga, Pasteurella; human bite/IVDU → Eikenella; water exposure → Aeromonas (freshwater); saltwater → Vibrio vulnificus
• Based on 1) purulence and 2) severity. Erythema may worsen before improves; should improve w/ 72h of appropriate antibiotics.
• If non-purulent w/ MRSA risk factors (IVDU, Prev infx/colonization, Abx in prev 8wks, DM, Hosp. in 1yr, athletes, staff, children at daycare, prisoner, military, LTC facilities, MSM): add empiric PO/IV MRSA coverage
• Additional coverage: anaerobes (if necrosis, putrid smell, crepitus, certain diabetic infections [see below]); GNRs (cirrhosis w/severe infection, immunocomp, certain diabetic infections [as below]); PsA (neutropenic, trauma, post-op)
• Duration: 5 days; up to 14 days if delayed signs of improvement. Take pictures and draw margin lines to track progress.
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