Cellulitis: Difference between revisions

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Revision as of 23:51, 14 August 2019

Cellulitis

Definition

  • Infection of superficial skin and soft tissue

Etiology

  • Streptococcus pyogenes (much more common)
  • Staphylococcus aureus (especially if purulent)
  • Rare, depending on exposures:
    • Hand or foot puncture: Pseudomonas aeruginosa
    • Facial cellulitis in children: Haemophilus influenzae
    • Human bite wounds: Anaerobes, Eikenella, viridans-group Streptococcus
    • Cat or dog bites: Pasteurella multocida
    • Saltwater exposure: Vibrio vulnificus (e.g. injury on coral)
    • Fresh- or saltwater exposure: Aeromonas hydrophila (e.g. leech bites)
    • Butchers: Erysipelothrix (erysipeloid)

Differential Diagnosis

  • Skin and soft tissue infections
    • Cellulitis (Strep/Staph)
    • Erysipelas (usually Strep)
    • Abscess (usually Staph)
    • Folliculitis (usually Staph or Pseudomonas): warm compresses and mupirocin ointment
    • Impetigo (usually Staph): watchful waiting, or topical or systemic antibiotics
    • Carbuncles
    • Necrotizing fasciitis
  • Other disease
    • Deep vein thrombosis
    • Gout (if over a joint)
    • Erythema nodosum
  • For an exhaustive list, see [Cellulitis mimickers](Cellulitis mimickers.md)

Presentation

  • Hot, red, swollen, tender area of skin with poorly demarcated margins
  • With or without pus and/or bullae
  • Legs more common than elsewhere

Management

  • Source control: drain any abscess
  • Antibiotics for 5-7 days
  • Purulent SSTI
    • Cephalexin or cefazolin are good first-line empiric choices
    • Doxycycline or vancomycin can also be considered
  • Non-purulent SSTI
    • Cephalexin 500mg po qid or cefazolin 1-2g IV q8h for 5-7 days
    • If penicillin allergy
      • Clindamycin300mg po qid
      • Moxifloxacin 400mg po daily
      • Linezolid 600mg po bid
      • Clindamycin 600mg IV tid
      • Vancomycin 1g IV q12h
  • Non-resolving cellulitis
    • Bug-drug mismatch
    • Resistance
    • Poor antibiotic choice
    • Unusual organism
      • Water exposure (fresh- or saltwater)
      • Fish
      • Shellfish, meats, hides
      • IV drug use
      • Animal or human bites
    • Poor adherence/absorption/distribution
    • Wrong diagnosis
    • Impatience!
  • Complications of infection
    • Abscess (drain it)
    • Deep infection
    • Metastasis

Prophylaxis