What is the diagnosis and treatment for necrotizing fasciitis?

From the Guidelines

Necrotizing fasciitis should be diagnosed based on clinical assessment, laboratory tests, and surgical exploration, with immediate treatment involving aggressive surgical debridement and broad-spectrum intravenous antibiotics, such as a combination of piperacillin-tazobactam, vancomycin, and clindamycin, as recommended by the Infectious Diseases Society of America 1.

Diagnosis

Diagnosis of necrotizing fasciitis involves clinical assessment for symptoms like severe pain, swelling, redness, fever, and skin changes, along with laboratory tests, such as elevated white blood cell count and C-reactive protein, and imaging studies, including CT and MRI scans 1.

• Clinical features that suggest involvement of deeper tissues include:
  • Severe pain that seems disproportional to the clinical findings
  • Failure to respond to initial antibiotic therapy
  • The hard, wooden feel of the subcutaneous tissue, extending beyond the area of apparent skin involvement
  • Systemic toxicity, often with altered mental status
  • Edema or tenderness extending beyond the cutaneous erythema
  • Crepitus, indicating gas in the tissues
  • Bullous lesions
  • Skin necrosis or ecchymoses

Treatment

Treatment requires aggressive surgical debridement to remove all infected tissue, which may need multiple operations, and broad-spectrum intravenous antibiotics should be started immediately, typically including a combination of piperacillin-tazobactam (4.5g every 6 hours), vancomycin (15-20mg/kg every 8-12 hours), and clindamycin (600-900mg every 8 hours) to cover common causative organisms like Group A Streptococcus, Staphylococcus aureus, and anaerobes 1.

• Antibiotics are adjusted based on culture results and continued for 2-3 weeks.
• Supportive care includes fluid resuscitation, pain management, and possibly hyperbaric oxygen therapy.
• The infection has a mortality rate of 20-40%, with better outcomes linked to early diagnosis, prompt surgical intervention, and appropriate antibiotic therapy, as noted in the guidelines 1.
• Patients often require intensive care monitoring and may need skin grafts or reconstructive surgery after the infection resolves.

From the Research

Diagnosis of Necrotizing Fasciitis

• The diagnosis of necrotizing fasciitis is often challenging due to the lack of specific clinical features in the initial stage of the disease 2, 3, 4.
• A high index of clinical suspicion is necessary for early diagnosis, as the disease can be easily underestimated or confused with cellulitis or abscess 2, 5.
• Clinical features that may aid in early diagnosis include:
  • Swelling (80.8% of patients) 5
  • Pain (79.0% of patients) 5
  • Erythema (70.7% of patients) 5
  • Pain out of proportion to physical findings 5
  • Failure to improve despite broad-spectrum antibiotics 5
  • Presence of bullae in the skin 5
  • Gas in the soft tissue on plain X-ray (although this occurs in only 24.8% of patients) 5
• Diagnostic tools that may be used to facilitate and hasten the diagnosis of necrotizing fasciitis include:
  • Laboratory risk indicator for necrotizing fasciitis (LRINEC) score 4
  • Transcutaneous tissue oxygen saturation monitoring 4
  • Magnetic resonance imaging (MRI) 4
  • Frozen section biopsies 4
  • Imaging techniques, such as plain X-ray to detect gas in the soft tissue 5

Treatment of Necrotizing Fasciitis

• Immediate and extensive radical debridement of necrotic tissues is mandatory once the diagnosis is suspected 2.
• Appropriate antibiotics and intensive general support are also crucial to avoid massive systemic diffusion of the infective process and to achieve successful treatment 2, 6.
• Early surgical exploration is the best approach in uncertain cases, as delayed recognition and treatment can lead to high mortality rates 2, 5.