Necrotising Fasciitis

Question 1

What is Necrotising Fasciitis?

Answer 1

SC soft-tissue infection which may extend to deep fascia but NOT underlying muscle
A form of infectious gangrene

Question 2

What are the 2 types of Necrotising Fasciitis?

Answer 2

T1: POLYmicrobial infection (anaerobe e.g. Bacteriodes or Peptostrep + facultative anaerobe e.g E.coli, enterobactoer, klebseiella)
T2: MONOmicrobial infection (strep pyogenes (GAS), staph A, MRSA, Aeronmonas hydrophilia + vibrio vuknificus)

Question 3

Describe the pathophysiology of Necrotising Fasciitis

Answer 3

Bacteria introduced into skin + soft tissue from minor trauma, puncture wounds, or surgery.
In up to 20% of cases no primary site of infection identified.
Infection extends through fascia but not into underlying muscle

Question 4

List 9 risk factors for Necrotising Fasciitis

Answer 4

Cutaneous injury, surgery or trauma  
DM  
PVD 
Immunocompromised 
Chronic renal/ hep insufficiency  
Chickenpox 
Herpes zoster  
IV drug use  
Certain meds (e.g. corticosteroids)

Question 5

Describe the epidemiology of Necrotising Fasciitis

Answer 5

T1 is more common than T2

Question 6

Give 5 symptoms of Necrotising Fasciitis

Answer 6

Anesthesia or severe pain over site of cellulitis  
Lightheadedness
N+V
Delirium
Palpitations

Question 7

Give 5 signs of Necrotising Fasciitis

Answer 7

Discoloration of skin 
Fever
Tachycardia
Tachypnoea
Hypotension

Question 8

List 4 investigations for Necrotising Fasciitis

Answer 8

Bloods
Blood + tissue culture
XR/CT/MRI if clinically appropriate, may show abnormalities of soft tissue
Surgical inspection, exploration + drainage of infected tissue

Question 9

What bloods are taken for Necrotising Fasciitis?

Answer 9

High WBC (if v. low may be a sign of sepsis) 
Systemic infection indications:
Hyponatremia
High urea
High cr
High crp 
High CK
High Lactate

Question 10

What provides a definitive diagnosis of Necrotising Fasciitis?

Answer 10

+ve blood and tissue cultures