Ecthyma gangrenosum

Background

• Necrotizing skin ulcers secondary to bacteremia in immunocompromised patients, traditionally caused by Pseudomonas aeruginosa

Microbiology

• Pseudomonas aeruginosa is by far the most common cause (75%)1
  • Likely the only cause in immunocompetent patients2
• Other bacteria (15%)
  • Aeromonas hydrophila (4%)
  • Stenotrophomonas maltophilia (2.4%)
  • Escherichia coli (2.4%)
  • Burkholderia cepacia
  • Pseudomonas stutzeri
  • Klebsiella pneumoniae
  • Citrobacter freundii
  • Staphylococcus aureus
  • Staphylococcus epidermidis
  • Non-tuberculous mycobacteria
• Fungi (10%)
  • Fusarium solani, likely the most common fungal cause
  • Candida albicans
  • Candida tropicalis
  • Mucor pusillus
  • Scytalidium dimidiatum
  • Metarhizium anisopliae

Clinical Manifestations

• Almost exclusively in immunocompromised patients with pseudomonal bacteremia
• Presents with gray macule or papule with surrounding erythema followed by progression to necrosis with black ulceration and eschar with erythematous halo