Necrotising fasciitis

Question 1

What is necrotising fasciitis?

Answer 1

Life-threatening subcutaneous soft tissue infection that requires a high index of suspicion for diagnosis
“inflammation of epidermis, dermis, underlying tissue”

Question 2

What are the different types of necrotising fasciitis a patient can have?

Answer 2

1. Type I ⇒ polymicrobial infection caused by mixed aerobes and anaerobes. More common, often occurs post-surgery in diabetics
2. Type II ⇒ monomicrobial infection caused by Streptococcus pyogenes

Question 3

What are the risk factors for necrotising fasciitis?

Answer 3

• immunosuppression (diabetes)
• IVDU ( intravenous drug use)
• cutaneous trauma
• surgery
• varicella zoster infections
• Impaired skin barrier
• Pressure
• Fricition
• Exposure to infectious agents

Most commonly affected site is the perineum ⇒ Fournier’s Gangrene
- Risk Factor for this is use of an SGLT-2 inhibitor (-flozins) in type 2 diabetics. Inhibits SGLT-2 co-transporter in PCT, increasing urinary excretion of glucose (and reducing glucose, hence increases chance of developing a urinary and genital infection, including necrotising fasciitis.)

Question 4

What are the presenting symptoms and signs of necrotising fasciitis?

Answer 4

• Acute Onset
• Anaesthesia or Severe Pain over site of infection
• Oedema (Swelling) and Erythema
• Systemic signs of infection → fever, palpitations, tachycardia, tachypnoea, hypotension, light-headedness, N&V
• Delirium and Crepitus-Crepitus is when there is a sensation or noise when you move a joint which can be described as clicking, cracking or popping (advanced cases)

Often presents as rapidly worsening cellulitis with pain out of keeping with physical features

Question 5

What investigations are used to diagnose/ monitor necrotising fasciitis?

Answer 5

1. Surgical Exploration → should be done before cultures
2. Blood and Tissue Cultures, gram stain

Question 6

What can cause necrotising fasciitis?

Answer 6

Infections, autoimmune response

Question 7

How is necrotising fasciitis managed?

Answer 7

1. Urgent Surgical Debridement → repeated as necessary until patient has no necrotic tissue remaining
2. IV Antibiotics → start as empirical until you have obtained blood cultures, then tailor to causative organism

Question 8

What complications may arise from necrotising fasciitis?

Answer 8

• Mortality 
• Skin loss and scaring 

Question 9

Describe the prognosis of necrotising fasciitis

Answer 9

Mortality is higher in patients who develop shock and end-organ damage, approaching 50% to 70%