Necrotising soft tissue infections are a highly dangerous type of skin and soft tissue disease that requires early and aggressive surgical debridement and antimicrobial management.
Clinical features often include wound pain, a foul watery discharge, skin blistering, and rapid progression. The appearances of the skin wound may initially seem not to support the seriousness of the Necrotising infection beneath, which often contributes to diagnostic delay. Soft tissue gas, detected clinically or radiologically, is a classic sign, but its absence does not exclude the presence of Necrotising infection.
Necrotising fasciitis spreads rapidly through the soft tissue and produces severe systemic sepsis. Progression to septic shock, multiple organ failure, and death ensues if aggressive treatment is not instituted immediately. Even with timely and appropriate treatment, death from Necrotising soft tissue infections is well recognised.
Type 1 Necrotising fasciitis usually follows surgery or trauma and progresses more slowly than other forms. Its usual onset is about 7 days after the insult.
Type 2 Necrotising fasciitis is usually due to Group A Streptococcal disease and is associated with surgery, minor trauma and secondary infection of varicella. It is characterised by progressing necrosis of multiple tissue layers, no gas with often very rapid progression and profound shock.
There is also Clostridial myonecrosis (gas gangrene) that is associated with trauma, surgery or spontaneous development sometimes related to cancer.
Most patients present with signs of inflammation such as erythema, swelling, and pain at the site. Severe pain disproportionate to local findings and in association with systemic toxicity is typical of Necrotising fasciitis. However, non-specific symptoms can present at first, which often causes the diagnosis to be missed. As the infection progresses, the skin becomes increasingly tense and erythematous with indistinct margins. It may change colour sequentially from a red-purple to a dusky blue before progressing to necrosis with the formation of bullae and eventually becoming haemorrhagic with the presence of marked bruising. Symptoms may develop over a period of hours to several days.
Treatment consists of four main interventions:
- Early and aggressive surgery that is repeated as often as necessary
- Appropriate antibiotics
- Full supportive care including critical care where necessary
- Consideration of hyperbaric oxygen therapy
In almost all cases there will be significant residual scarring and in some the consequences of post survival of septic shock such as renal failure may persist, including in some patients psychological sequelae. In recent years there had been some improvement in the death rates associated with Necrotizing fasciitis which is probably due to earlier recognition and improved management and supportive measures.
The information provided in this article is from Professor Robert Masterton a a Consultant Microbiologist. A strong advocate of evidence-based medicine Professor Masterton has sat on six United Kingdom (UK) guideline groups and chaired the UK Working Party that published guidelines on Hospital Acquired Pneumonia in 2008.