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What is Necrotising Fasciitis

The term necrotising fasciitis comes from the words ‘necrosis’, which means death of a portion of tissue (flesh) and ‘fascia’, the name given to the sheets or bands of fibrous tissue which enclose and connect the muscles. NF is a severe infection involving the soft tissue below the skin, particularly the fascia. It can affect any part of the body but it is most common on the legs. This section provides information on how necrotising fasciitis happens, the signs and symptoms and treatment and aftercare.


What causes Necrotising Fasciitis

NF may be caused by a number of bacteria; one of these is Streptococcus pyogenes (also known as Strep. pyogenes or Group A streptococcus). Streptococcal necrotising fasciitis is a rare condition with approximately 1000 reported cases a year in the United Kingdom.

NF arises most often spontaneously (without prior cause) in patients living in the community and often in previously perfect health. Cuts or grazes to the skin may be a source, but such damage may be trivial or may go unnoticed. Sometimes it may occur in hospitalised patients after surgery. When it arises in the community, the source is usually the patient’s own Strep pyogenes strain.

NF may begin in an established wound (following either injury or surgery) or in broken skin such as a leg ulcer. Excessive pain is an early warning symptom. Bacteria spreads very rapidly in the tissues below the skin surface, well ahead of any visible changes in the overlying skin.

Necrotising Fasciitis risk factors

Recent investigations have suggested that patients taking painkillers of the type known as ‘Non-Steroidal Anti-Inflammatory Drugs’ (NSAIDs), may be slightly more at risk of NF. This has yet to be proved. Other risk factors include diabetes, age over 50 years, steroid treatment, high blood pressure, obesity and alcoholism. Strep. pyogenes also appears to have a particular liking for the skin spots of chicken pox, and NF may occasionally complicate this infection.

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Risk factors identified:


Non-Steroidal Anti-Inflammatory Drugs’ (NSAIDs)




Over 50s




Steroid treatment


High blood pressure




Skin spots / chicken pox

Bacteria related to Necrotising Fasciitis

There are several bacteria that may be related to Necrotising Fasciitis. These include:

You can find out about each by clicking the bacteria above.

Signs and symptoms of Necrotising Fasciitis

Due to the speed with which severe streptococcal infections can spread, early diagnosis of necrotising fasciitis and severe streptococcal infections will Increase the chance of survival, with minimal damage to the patient.

Necrotising Fasciitis when caused by streptococcal pyogenes can behave in a very fast, aggressive manner and may begin in an established wound or in broken skin and bruising. True statistics are difficult to obtain due to late diagnosis and the mortality rate of this horrific disease can be as high as 76%.

Bacteria spreads very rapidly in the tissues below the skin and infection progresses at inches per hour. The patient rapidly becomes unwell with flu-like symptoms, with possible vomiting and diarrhoea.

If not treated very quickly the skin over the affected area becomes dusky and purple, blisters may form and the skin dies. By this stage the infection has penetrated into the underlying tissues and the patient often develops toxic shock syndrome with collapse, low blood pressure and failure of the liver, kidneys and other vital organs.

Early external symptoms:


Usually a minor trauma, skin opening or wound, (possibly Cellulitis or Ulcers) PLEASE NOTE, the wound does not necessarily appear infected.


Pain may develop at the site of the injury, or any other part of the body.


The pain is usually disproportionate to the injury and may start as something akin to a muscle pull, but becomes more and more painful.


Flu like symptoms begin to occur, such as diarrhoea, nausea, fever, confusion, dizziness, weakness, and general malaise.


Intense thirst occurs as the body becomes dehydrated.


The limb, or area of the body experiencing pain begins to swell, and will show a red flaky rash.

The biggest symptom is all of these symptoms combined. In general you will probably feel worse than you’ve ever felt and not understand why.


Hopefully by this stage the patient will have received at least some antibiotic treatment as the internal symptoms may be advanced at this stage.

Advanced & Critical symptoms:


The limb may begin to have a large, navy blue rash, that will become blisters filled with blackish fluid.


Blood pressure will drop severely. With low blood pressure, the blood is unable to deliver vital oxygen to the major organs.


The body begins to go into toxic shock from the toxins the bacteria are giving off.


Unconsciousness will occur as the body becomes too weak to fight off this infection.

It is vital that the symptoms be recognised before this stage and treatment must be sought immediately by the use of antibiotics. Extensive infection may require surgery to remove the infected area and possibly limbs.

Conditions related to Necrotising Fasciitis

Necrotising Fasciitis is a condition related to the infection, not the infection itself. Other complications related to infection include:

You can read more about these conditions here.

Treatment, aftercare and skin grafts

Immediate interventions

The key to patient survival is swift recognition and immediate treatment. Once recognised, high doses of antibiotics are required, but these on their own are insufficient to halt the infection with its severe local and general effects. The most important element of treatment is the surgical removal of the infected dead and dying tissue. If this is not done and done quickly, the infection continues to advance. Many patients who survive the first 48 hours need additional operations during and after this time to remove further infected tissue.

Other measures

Sometimes it may be necessary to check relatives or others in contact with the patient to see if they are carrying the same strain of Strep. pyogenes. This is normally done by taking nose and throat swabs. Occasionally other swabs may be advised. Contacts found to be carrying a Strep.pyogene strain may be treated with oral antibiotics.

Treatment outcomes

Despite the best treatment, the infection is so severe that the death rate is still around 30-50%. Survivors may need amputation because of extensive areas of tissue being destroyed. NF can be severely disfiguring, and patients may need extensive plastic surgery and skin grafting to achieve the best possible functional and cosmetic result.

Understanding skin grafts

A skin graft is when damaged skin is removed and is replaced with healthy skin taken from another part of your body (or donor area). Split skin grafts are the most common type of skin graft using the epidermis (outer layer of skin) and upper layers of the dermis (second layer).

A donor area is where the skin is harvested or taken from another part of your body and used to cover the affected area. This area heals within 10 – 14 days. The skin is usually taken from the thighs, buttocks or other areas. You will be able to discuss the proposed donor site with the medical staff.

The graft will be secured in different ways for the different patients. It may be stapled, stitched or glued in place, or simply laid onto the area.

The donor area will usually be left for 10 – 14 days, but sometimes may be inspected with your graft. Often the donor area will ooze fluid and may smell this is quite normal. As the healing process of the donor area continues you may experience some pain, and especially itching, when walking, and at other timed also. As time goes on the dressing will dry out, harden and separate from the donor area, it may even fall off. This is also quite normal, as the dressing is designed to fall off when the donor site is healed.

By eating a healthy diet with plenty of protein intake. By avoiding smoking, this slows or stops your healing by slowing oxygen and blood supply to the grafted area.

After skin grafts, scar formation is inevitable. The scar will never look exactly like ordinary skin, but with proper care and medical management during the first 18 months after your burn, the scarring can be reduced to a low level. It takes up to 18 months for a scar to mature, usually leaving only a pale, soft flat and supple scar. During this time there are several important steps that may be taken to treat your possible scars, and your consultant may order special exercises, creams, splints or pressure garments for you. All this will be made clear by the nursing staff prior to your discharge.

The grafted area is usually left dressed for five-seven days after the operation. It will be securely wrapped up with dressings. Some patients may also require a plaster of Paris to prevent additional movements near the joints. It is important that the graft is moved as little as possible in the first 48 hours, giving the skin graft a chance to take. In some cases you will be advised to stay in bed. Sometimes a graft may be left without dressing. If so, the graft will be looked after by nursing and medical staff, and will be cleaned and inspected regularly.

The first dressing change is carried out five – seven days after the operation. If staples were used this is when they are removed. This may be painful, so your usual painkillers will be given. If sutures were used they may be removed, but not always. The Doctor will examine your graft and decide on the final part of your treatment. You will probably be given a lighter dressing, and will not have to have another plaster of Paris applied.

If you have questions about skin grafts which haven’t been answered here, please contact us at [email protected]

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