What are the signs and treatment of necrotizing fasciitis?

Signs and Treatment of Necrotizing Fasciitis

Necrotizing fasciitis requires immediate surgical debridement as the primary treatment modality, along with broad-spectrum antibiotics and aggressive supportive care to reduce mortality. 1

Diagnostic Signs

Key Clinical Features

• Severe pain disproportionate to physical findings (cardinal sign)
• Hard, wooden feel of subcutaneous tissue extending beyond visible skin involvement
• Systemic toxicity with altered mental status
• Edema or tenderness extending beyond cutaneous erythema
• Failure to respond to initial antibiotic therapy
• Crepitus (gas in tissues)
• Bullous lesions
• Skin necrosis or ecchymoses 1

Diagnostic Challenges

• Early diagnosis is difficult as overlying skin may initially appear normal or resemble cellulitis
• The most important diagnostic element is clinical judgment and high index of suspicion 1
• Definitive diagnosis is made during surgery by appearance of fascial planes:
  • Swollen, dull gray fascia with stringy areas of necrosis
  • Thin, brownish exudate
  • No discrete pus
  • Extensive undermining of surrounding tissues
  • Tissue planes easily dissected with finger or blunt instrument 1

Imaging Considerations

• CT or MRI may show edema along fascial planes but sensitivity/specificity are limited
• Imaging should not delay definitive diagnosis and treatment 1
• CT may be helpful in severe cases showing necrotic skin and soft tissue gas 2

Treatment Approach

Surgical Management (Primary Treatment)

• Immediate surgical debridement is the cornerstone of treatment 1

• Indications for surgery:

  • Clinical findings suggestive of necrotizing fasciitis
  • Failure of cellulitis to respond to antibiotics
  • Profound toxicity, fever, hypotension
  • Advancement of infection during antibiotic therapy
  • Skin necrosis with easy fascial dissection
  • Presence of gas in soft tissues 1

• Return to operating room every 24-36 hours for additional debridement until no further necrotic tissue is present 1

• Delays in surgical intervention correlate with increased mortality 2, 3

Antimicrobial Therapy

• Begin broad-spectrum antibiotics immediately when diagnosis is suspected 1

• Empiric treatment for polymicrobial necrotizing fasciitis should include:

  • Coverage for MRSA: vancomycin, linezolid, or daptomycin
  • PLUS one of the following:
    • Piperacillin-tazobactam
    • A carbapenem (imipenem-cilastatin, meropenem, ertapenem)
    • Ceftriaxone plus metronidazole
    • A fluoroquinolone plus metronidazole 1

• For group A streptococcal necrotizing fasciitis/toxic shock syndrome:

  • Combination of clindamycin AND penicillin
  • Clindamycin suppresses toxin and cytokine production 1

• Continue antibiotics until:

  • No further debridement needed
  • Clinical improvement
  • Fever absent for 48-72 hours 1

Supportive Care

• Aggressive fluid resuscitation is essential as wounds discharge copious tissue fluid 1
• Intensive care monitoring for severe cases 1
• Consider risk stratification to identify patients needing critical care 1

Prognostic Factors

Poor Prognostic Indicators

• Delayed diagnosis and treatment 3, 4
• Advanced age 3
• Presence of anaerobic bacteria (associated with increased surgical revisions) 2
• Poor white cell response (common in diabetic patients) 5
• Laboratory abnormalities: high serum urea/creatinine, low hemoglobin 5
• ASA classification IV-V (increased ICU stay, ventilation duration, and mortality) 2

Mortality Considerations

• Overall mortality rates range from 33-73% 3
• Early intervention significantly improves survival 3, 5
• Mean interval between symptom onset and hospital admission is significantly shorter in survivors (2 days) compared to non-survivors (7.3 days) 3

Special Considerations

• Conservative management with antibiotics alone has been reported in select cases of periorbital necrotizing fasciitis 6, but this approach is not standard and surgical debridement remains the mainstay of treatment for most cases
• Polymicrobial (Type I) infections are most common, often involving both aerobic and anaerobic organisms 1, 2
• Involvement of anaerobic bacteria requires more aggressive and frequent surgical debridement 2