Necrotising Fasciitis

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | References

Definition

Necrotising fasciitis is a severe, rapidly progressing bacterial infection that causes the death of soft tissue. It is often referred to as "flesh-eating disease."

Aetiology

Necrotising fasciitis is caused by several types of bacteria, often in combination, including:

• Group A Streptococcus (GAS)
• Staphylococcus aureus, including MRSA
• Clostridium species
• Escherichia coli
• Klebsiella species

Pathophysiology

The pathophysiology of necrotising fasciitis involves:

• The bacteria enter the body through a break in the skin, such as a cut, scrape, or surgical wound.
• The infection rapidly spreads along the fascial planes, causing tissue necrosis.
• Exotoxins and enzymes produced by the bacteria lead to extensive tissue damage, systemic toxicity, and sepsis.

Risk Factors

• Diabetes
• Immunocompromised states
• Chronic illness (e.g., liver disease, kidney disease)
• Recent surgery or trauma
• Intravenous drug use
• Peripheral vascular disease

Signs and Symptoms

The signs and symptoms of necrotising fasciitis include:

• Severe pain that is disproportionate to the clinical findings
• Swelling and erythema
• Rapid progression of symptoms
• Fever and chills
• Crepitus (a crackling sensation under the skin)
• Blisters or bullae on the skin
• Necrosis (blackening) of the skin
• Signs of sepsis, including hypotension and altered mental status

Investigations

Specific investigations to diagnose necrotising fasciitis include:

• Blood tests: Full blood count (FBC) showing leukocytosis, elevated C-reactive protein (CRP), and other markers of infection.
• Imaging: X-ray, CT scan, or MRI to assess the extent of tissue involvement and identify gas in the soft tissues.
• Tissue biopsy: Histological examination to confirm the diagnosis and identify the causative organisms.
• Microbiological cultures: From blood, wound, or tissue samples to identify the bacteria and guide antibiotic therapy.

Management

Primary Care Management

• Immediate referral: Suspected cases should be referred urgently to secondary care for further assessment and management.
• Initial supportive care: Ensuring stabilisation of the patient, including fluid resuscitation and pain management, while arranging urgent transfer to hospital.

Specialist Management

• Intravenous antibiotics: Broad-spectrum antibiotics initiated promptly, often including a combination of agents such as penicillin, clindamycin, and an aminoglycoside or carbapenem.
• Surgical debridement: Urgent and repeated surgical removal of necrotic tissue is critical to control the infection.
• Intensive care support: Management of sepsis and multi-organ failure in an ICU setting if required.
• Hyperbaric oxygen therapy: May be considered as an adjunctive treatment in some cases.
• Wound care: Ongoing management of the wound following debridement, including dressing changes and possibly reconstructive surgery.

References

1. NHS (2024) Necrotising fasciitis. Available at: https://www.nhs.uk/conditions/necrotising-fasciitis/ (Accessed: 24 June 2024).
2. Centers for Disease Control and Prevention (2024) Necrotizing Fasciitis: A Rare Disease, Especially for the Healthy. Available at: https://www.cdc.gov/groupastrep/diseases-public/necrotizing-fasciitis.html (Accessed: 24 June 2024).
3. World Health Organization (2024) Necrotizing fasciitis. Available at: https://www.who.int/health-topics/necrotizing-fasciitis (Accessed: 24 June 2024).
4. British Medical Journal (2024) Necrotising Fasciitis: clinical features, diagnosis, and management. Available at: https://www.bmj.com/content/350/bmj.h1827 (Accessed: 24 June 2024).

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