Necrotising fasciitis

This is a rare infection in which the microbes settle not in the skin but underneath it, in the thin sheets of tissue that wrap the muscles. Along those sheets the infection spreads sideways, poisoning the tissue with its toxins and closing off the vessels that feed the skin. For the first few hours there is almost nothing to see from outside, and that is the trap: a leg that still looks normal hurts far more than such a small wound could ever explain. This illness moves in hours rather than days, and the only thing that stops it is urgent surgery. What is asked of the patient and of the people around them is simple: do not talk yourself into waiting until morning.

How it begins

There is usually a starting point: a cut, a graze, a bite, a burn, an injection site, a surgical wound. Sometimes the way in is so small that nobody remembers it, and occasionally there is none at all — the microbe arrives through the bloodstream after a throat infection or a blow to the muscle.

The first and most important sign is pain out of all proportion to the injury. A scratch on the shin, and the pain is such that the person cannot sleep or put weight on the leg; it grows from hour to hour and does not answer to ordinary painkillers. Alongside it come:

• swelling that spreads well beyond the reddened area, with skin tight and shiny, as though filled;
• a wooden hardness on feeling the limb: not soft tissue under the fingers but a plank;
• fever, shivering, aching and weakness — the feeling of a heavy flu;
• a fast pulse, thirst and little urine;
• sometimes the opposite: a patch of skin suddenly loses feeling and goes numb, because the nerve endings are dying.

After a few hours, or by the end of the first day, what appears can no longer be missed: purple, bluish, grey or bronze patches, blisters with cloudy or blood-stained fluid, black areas of dead skin. On dark skin these changes are harder to see, so go by the pain, the swelling and the person's general state rather than by colour. That is also when confusion, drowsiness and indifference set in — a sign that the toxins are now acting on the whole body.

When to call an ambulance

Call an ambulance (in Spain, Italy, Portugal, Poland and Ukraine the single number is 112) if someone with a wound, a graze, a bite or a recent surgical scar develops any one of these:

• pain worse than it ought to be, rising quickly, with painkillers making no difference;
• swelling and hardness spreading before your eyes — visibly further on within an hour or two;
• a high temperature with shivering, vomiting, diarrhoea and marked weakness;
• skin nearby turning grey or purple, blistering or going numb;
• confusion, difficulty rousing the person, dizziness on trying to stand.

While you wait: do not apply heat, do not cut or open anything yourself, and give nothing to eat or drink, because an anaesthetic may be needed. Draw round the edge of the redness with a pen and note the time — that tells the team more about the speed than any description. Gather up the medicines the person takes, and do not drive to hospital yourself: blood pressure can drop sharply on the way.

One more thing. If the wound was looked at in the morning, antibiotic tablets were prescribed and you were sent home, and by evening the pain and swelling have grown, this is not a case of "the medicine needs time". It is a reason to go back and say out loud that things are worse.

How it differs from an ordinary skin infection

Erysipelas and cellulitis are hundreds of times more common and look similar: redness, swelling, fever. The difference lies in three things.

Pain. In an ordinary infection it matches the look of the wound and eases with the usual remedies. Here it is out of proportion and does not let up.

Speed. Erysipelas unfolds over a day or two; necrotising fasciitis over hours. A pen line that the redness has crossed by several centimetres within an hour is an alarm signal in itself.

General condition. With an ordinary skin infection the person is ill but not broken: they walk, eat and answer questions. Here the severity of the illness runs ahead of anything visible on the skin.

A word about painkillers. Anti-inflammatory drugs such as ibuprofen bring the temperature down and blunt the pain — that is, they rub out precisely the two signs by which this illness is recognised. Taking them to get through to the morning is a poor idea; if a wound hurts so much that a tablet is unavoidable, that alone is reason to be seen today.

Where the infection comes from

The organism varies. The commonest is group A streptococcus, the same microbe that usually causes a throat infection: under the skin it releases toxins and travels along the fascia at speed. The second pattern is a mixture of several bacteria, including those that live without air, which is more usual in people with diabetes, after abdominal surgery and in the area of the perineum. Separate again are the microbes of warm sea and brackish water, which enter a fresh wound while swimming or while cleaning fish and shellfish.

The way in can be anything: cuts and grazes, burns, insect and animal bites, injection sites, surgical wounds, childbirth. Children have a situation of their own: the infection can complicate chickenpox, so a fresh high temperature on the fifth or sixth day of the illness together with severe pain around one of the spots means a child must be seen straight away.

Any healthy person can be affected, but some conditions raise the risk:

• diabetes, especially with foot wounds that heal badly;
• treatment that suppresses the immune system, and cancer;
• cirrhosis of the liver, chronic kidney disease, marked obesity;
• disease of the leg vessels and lymphoedema;
• injecting drug use;
• old age and poor nutrition.

The illness is not passed on through everyday contact: it is safe to be beside the patient. The streptococcus itself, however, does move from person to person, so if someone in the household has had a severe streptococcal infection, the others should pay closer attention to their own wounds and not shrug off a sore throat with a high temperature.

How the diagnosis is made

Here the diagnosis is made not by a test but by the doctor at the bedside, and confirmed by the surgeon in theatre. This is worth understanding, because waiting for "objective evidence" costs time that is not available.

The decisive procedure is surgical exploration of the wound. The surgeon opens the tissues and looks at the fascia: in this illness it is grey and dull, separates easily under a finger, bleeds poorly, and cloudy fluid with a characteristic smell comes from the incision. Samples are taken for culture at the same time, so that the antibiotic can be narrowed down later.

Everything else is supporting evidence. Blood tests show high markers of inflammation, clotting disturbance, low sodium, raised lactate and signs of kidney strain; that pattern strengthens the suspicion, but normal results do not rule the illness out. CT and ultrasound sometimes show gas in the tissues and fluid tracking along the fascia — if they do, that is nearly proof; if they do not, it means nothing. This is why sending someone with rapidly worsening pain and swelling for scans instead of to theatre is dangerous: the pictures may look calm in the very hour when the clock has moved to minutes.

How it is treated

Treatment has three parts, and the first is the one that counts most.

Surgery. The surgeon removes all dead tissue back to healthy, bleeding edges. One operation is rarely enough: the wound is left open and revisited every day or two until the spread stops. An early and sufficiently wide first operation affects the outcome more than any antibiotic. If the infection has run too far up a limb and threatens life, amputation becomes necessary — a hard decision, but sometimes the only one.

Antibiotics are given into a vein, several at once to cover every possible organism, always including one that shuts down the production of bacterial toxins. Once the culture result arrives, the regimen is narrowed.

Intensive care support. The toxins hit blood pressure, the kidneys and clotting, so fluids are needed, sometimes drugs to hold the blood pressure up, oxygen or a ventilator, and dialysis. In severe toxin-driven illness, donor immunoglobulins are given. Some centres add hyperbaric oxygen, which neither replaces nor delays the operation.

What comes afterwards

Once the infection has been stopped, a large open wound remains and the long part begins: dressings, sometimes negative-pressure wound treatment, then skin grafting. All of this takes weeks and months, and the early stage is exhausting.

Recovery rarely stops at the skin. Scars pull and restrict movement, and some muscle beneath them has gone, so rehabilitation starts early and continues for a long time. After amputation a prosthesis is fitted and has to be learned. Food matters too: a wound of that size only heals on a diet rich in protein and calories.

One thing deserves saying that usually goes unsaid. After an illness like this, nightmares, intrusive memories, fear of any scratch and low mood are common. That is not weakness or self-indulgence, it is an ordinary consequence of what happened, and psychologists and psychotherapists work with it — asking for that help is as normal as asking for a dressing change.

Online consultation

Plainly: if this illness is suspected, a remote appointment is not what is needed — an ambulance is. Nobody can examine, feel or measure the speed of spread through a screen, and an hour lost here is worth more than any consultation.

An online appointment is useful around the subject, though. With a wound, a burn or a bite, a doctor can go through the description and the photographs, say what to do with it, whether a tetanus booster is due, which signs mean it is turning septic and at what point to drop everything and go in. That is worth most to people with diabetes, lymphoedema or a weakened immune system, whose wounds need closer watching.

The second use is after discharge. Care of the wound and the scars, pain relief, when weight can go back on the limb, questions about food and recovery, anxiety and broken sleep are all handled well remotely, as is deciding which new complaint needs a face-to-face review.

This material is for information only and does not replace medical advice.