Necrotising fasciitis was first been described in soldiers during the American Civil war in the eighteenth century. This condition has been known by various names including phagadena gangrenosum, Meleney’s gangrene, Fournier’s gangrene (necrotising fasciitis of the perineum). The term necrotising fasciitis was first coined in 1952 by American Surgeon B Wilson.
Necrotising fasciitis is classified into three types based on the organisms involved. Type I is polymicrobial, type II is monomicrobial and type III by a specific pathogen namely marine Vibrio species (V. vulnificus). Bacteria associated with type I are a combination of gram-positive cocci (streptococci and staphylococci), gram-negative species (Escherichia coli, Acinetobacter, Pseudomonas and Klebsiella) and anaerobic organisms like Bacteroides and Clostridia .
NF is a rapidly progressing bacterial infection involving the subcutaneous tissues. The bacteria produce endotoxin and exotoxin  that leads to micro-vascular thrombosis , tissue ischaemia and liquefactive necrosis. This causes a systemic illness  often progressing to septic shock, multi-organ dysfunction and death. The condition is resistant to antimicrobial therapy due to poor drug penetration, hence leaving surgical debridement as the primary treatment option .
Previously reported predisposing factors included rheumatoid arthritis, SLE, type 2 diabetes mellitus, renal transplantation, chronic renal failure, injection IV drug use, immunosuppressive therapy and intramuscular injection with nonsteroidal anti-inflammatory drugs. Other factors include trauma, burns, insect bite, chronic skin ulcers and postoperative wound infection. Of these, type 2 diabetes is the commonest underlying medical condition and multiple needle punctures in IV drug users is the commonest trauma predisposing to NF .
The clinical picture and presentation of the patient may vary and hence can pose a diagnostic challenge at an early stage and hence requires a very high index of suspicion. The most common early signs are local erythema, warmth, induration, oedema and pain, which are also present in conditions like cellulitis and septic arthritis and hence the diagnostic dilemma. However, pain out of proportion to clinical signs associated with septic shock or failure to respond to broad-spectrum intravenous antibiotics should alert the clinician to possible NF. Patches of skin necrosis, crepitus and bullae with compromised haemodynamic status are alarming signs.
Ultrasound, CT or MRI scan can be done in suspicious cases. Wong et al.  devised the Laboratory Risk Indicator for Necrotising Fasciitis (LRINEC) score, which is a valuable diagnostic tool to distinguish necrotising fasciitis from non-necrotising skin infections. LRINEC score ≥ 6 had a positive predictive value of 92% in high-risk patients according to this study. Based on our patient’s initial blood reports, the LRINEC score was 6.
LRINEC score tool
C-reactive protein < 150
WBC cells/cu mm < 15
Haemoglobin g/dl > 13.5
Sodium mmol/L > 135
Creatinine mcg/L < 141
Glucose mmol/L < 10
Reproduced from: Wong CH, Khin LW, Heng KS; The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score: a tool for distinguishing necrotizing fasciitis from other soft tissue infections Crit Care Med. 2004, 32: 1535-1541. https://doi.org/10.1097/01.CCM.0000129486.35458.7D.
In suspected or established cases of NF, early surgical exploration and debridement with broad-spectrum intravenous antibiotics is considered key to successful treatment in NF . Surgical exploration can also establish the diagnosis of NF. The operative findings of greyish necrotic deep fascia, lack of resistance to blunt dissection, lack of bleeding of the fascia and presence of foul-smelling ‘dishwater’ pus aids in the confirmation of the diagnosis. Excised tissue should be sent for gram staining, culture and histology. Wound closure is carefully planned as early closure carries the risk of residual infection and poor healing.