Diagnosis

Necrotizing fasciitis

Etiology

Causes [tbd]

• Type I necrotizing fasciitis (80%): mixed infection (elderly patients)

  • Bacteroides, Clostridium, Peptostreptococcus, Enterobacteriaceae, Escherichia coli, Proteus, Pseudomonas, Klebsiella, Vibrio vulnificus, Group A beta-hemolytic streptococci, Haemophilus aphrophilus, S aureus, varicella infection and NSAIDs.

• Type II necrotizing fasciitis:

  • Group A beta-hemolytic Streptococcus (Streptococcus pyogenes) alone or in combination with Staphylococcus aureus

• Type III necrotizing fasciitis:

  • Vibrio or Aeromonas species (contaminated water or food)

• Combination with an underlying cause:

  • Diabetes

  • Atherosclerotic vascular disease

  • Venous insufficiency

Pathophysiology [why]

1. Streptococcal pyrogenic exotoxins are directly toxic --> release of cytokines

2. The infection typically travels along the fascial plane, which has a poor blood supply

   • Vascular occlusion --> ischemia --> tissue necrosis

   • Superficial nerve damage --> localized anesthesia

   • Sepsis due to systemic toxicity

3. The overlying tissues are initially unaffected --> delaying diagnosis and treatment

4. Skin affection after several days:

   • Color: Erythema with purple to bluish-gray hue

   • Texture: Indurated

   • Swollen, shiny, and warm in temperature

   • Painful out of proportion

   • Bullae

   • Cutaneous gangrene

Risk factors

• Trauma

• Surgery

• Insect bites

• Immunocompromised patients: diabetes mellitus, cancer, alcoholism, vascular insufficiencies, organ transplants, HIV infection, or neutropenia

Complications [why]

• Multiorgan failure

• Septic shock

• Loss of extremity

• Severe scarring

• Toxic shock

• Death

Epidemiology

Incidence per 100.000 [tbd][myi][rba]

Approach

• The Laboratory Risk Indicator for Necrotizing Infection Score ≥ 6p [why]

  • CRP > 150 (4p)

  • White cell count >25 (2p) >15 (1p)

  • Hemoglobin <11 (2p) <13.5 (1p)

  • Na < 135 (2p)

  • Creatinine > 140 (2p)

• Blood gas

• Urinanalysis

• Blood culture

• Tissue culture

• Biopsy

• PCR

• Ultrasound

• CT

• MRI

Treatment

1. Transferred immediately to the intensive care unit: [why]

   • Aggressive resuscitation with fluids and inotropes to maintain blood pressure

2. Antibiotics (wide-spectrum):

   1. Imipenem 1 g every 6 to 8 hours or Piperacillin/tazobactam 4 g every 6 hours

      Daptomycin 6 mg/kg QD

      Clindamycin 600 mg to 900 mg 4 times daily

   2. Meropenem 1 g IV every 8 hours

      Vancomycin 15 to 20 mg/kg/dose every 8 to 12 hours

      Clindamycin 600 mg to 900 mg 4 times daily.

3. Surgery without delay: extensive, wide debridement of all necrotic tissues

   • Wounds must be left open and packed with wet gauze for second look

4. Parenteral nutrition

Differential diagnoses

Cellulitis, Epididymitis, Erysipelas, Fournier gangrene, Gas gangrene, Inguinal hernia, Nonclostridial myonecrosis, Orchitis, Sepsis, Septic arthritis, Testicular torsion, Toxic shock syndrome