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Necrotising Fasciitis

Background

Necrotising fasciitis (NF) is a rare infection caused by bacteria and affecting deep tissue under the skin.

Risk factors for infection include lowered immunity, eg people with diabetes mellitus, cancer or receiving immunosuppressive treatments. Healthy children whose skin is broken by minor trauma or skin infection such as chicken pox are also at increased risk.

Credits

Last updated June 2016 by Dr Marina Morgan, Consultant Microbiologist, Royal Devon and Exeter Foundation Trust, Exeter, UK.

Although great care has been taken in the compilation and preparation of all entries to ensure accuracy, we cannot accept responsibility for any errors or omissions. Any medical information is provided is for education/information purposes and is not designed to replace medical advice by a qualified medical professional.

 

 

What are the symptoms?

NF usually affects legs and arms, but can occur anywhere on the body. The pain is usually almost unbearable - totally out of proportion to external signs because the infection begins deep under the skin, spreading along a thin membrane ('fascial plane')  near to the muscle. Eventually the thin membrane (fascia) dies, causing necrotising ('death of') fasciitis ('inflamed fascia') and  severe deep pain due to swelling and inflammation. As infection rises to the skin surface it causes discolouration which may be pinky-red, bruised or blistery. Very late in the infection numbness and areas of purple/blackness, bloody blisters of dead skin overlie the deeper dead tissue.

NF can be difficult to diagnose because initially there is not much to see and it can cause confusing symptoms. Toxins produced by Streptococci and Staphylococci  may cause vomiting and diarrhoea- hence easily misdiagnosed as a 'tummy upset' or food poisoning. Deep pain without any outward change in the skin is easily blamed on a muscle strain.

What are the causes?

All bacteria can cause NF, the worst cases being due to Streptococci, (especiallyS pyogenes, the type of streptococcus usually causing tonsillitis), Staphylococci, Clostridia and Vibrio species.

How is it diagnosed?

NF is characterised by severe pain out of proportion to what can be seen. Specialised scans, such as magnetic resonance imaging (MRI) or computed tomography (CT) may show deeper tissue changes and suggest the diagnosis of NF, but  a quicker and absolute diagnosis is made by opening up the tissues to see how deep the infection is, and whether the deeper tissues and fascia are healthy or not. Usually a small sample of tissue is sent for Gram stain (special staining allowing identification of the bacteria within minutes) and culture (where bacteria are grown and identified). Once the bacteria causing the infection is known, more targeted antibiotic treatment can be prescribed.

How is it treated?

Treatment for suspected NF should be started immediately. Initially, broad-spectrum antibiotics (antibiotics that can kill a wide range of bacteria) are used together with an antibiotic that will specifically stop toxin production from bacteria (eg clindamycin or linezolid). Surgical removal of infected dead tissue lessens the numbers of bacteria the body has to fight. Another way of inactivating toxins already produced and preventing 'toxic shock' and further tissue damage is to use intravenous immunoglobulin (IVIG), which is an injection of antibodies from blood donors. However, IVIG only helps in Streptococcal or Staphylococcal infections, so is not used in all NF cases.

Inheritance patterns and prenatal diagnosis

Is there support?

The Lee Spark NF Foundation

Email: via website
www.nfsuk.org.uk

The Foundation is a Registered Charity in England and Wales No. 1088094. It supports medical professionals, families and carers that have been affected by Necrotising Fasciitis and other Streptococcal infections. The Foundation publishes a quarterly newsletter and has a range of information available, including a medical training DVD. 

Group details last updated June 2016.

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