Necrotizing fasciitis: what are its causes?

Necrotizing fasciitis is a progressive infection of the skin and soft tissues that causes tissue necrosis. —Death of a group of cells. It affects the patient systemically and its prognosis is usually fatal.

According to the seminars of the Spanish Foundation of Rheumatology, the incidence of this clinical picture has increased in recent years, since it is estimated that it occurs in 1 out of every 100,000 inhabitants in European countries. In one third of patients this pathology leads to multi-organ failure.

As you can see, we are facing a serious infection that can lead to death. If you want to know its causes, how to avoid it and the available treatments, we encourage you to continue reading.

Symptoms associated with necrotizing fasciitis

Although the incidence of this clinical picture has increased, it is still considered a rare infection, but one of rapid progression and difficult diagnosis in early stages. As the journal Medisur indicates, this event affects the skin, the subcutaneous cellular tissue, the superficial and occasionally the deep fascia.

In addition to causing tissue death, it also causes local thrombosis and has severe systemic toxicity. According to the National Library of Medicine of the United States some of the most common signs of necrotizing fasciitis are the following:

  • A small reddish bump or spot on the skin spreading.
  • An area similar to a bruise that grows out of control and it is painful to the touch. Clear growth can sometimes be seen in less than an hour.
  • These areas acquire a blackish color which corresponds to the death of the tissue. The skin may break open and ooze fluid.
  • Other symptoms: fever, general malaise, sweating, chills, nausea, dizziness, weakness and even shock septic.

In general, the last named clinical signs correspond to a stage of bacteraemia – entry of bacteria into the blood – and septicemia. Thus, patients with advanced necrotizing fasciitis appear to be confused, disoriented, and severely mentally impaired.

Infections in the skin can spread to the subcutaneous tissue, which represents the gateway for the bloodstream.

To know more: The state of shock: causes and types

What is the cause?

The cause of necrotizing fasciitis is the invasion of a bacterium into the skin tissues of the patient. According to the Mexican Journal of Dermatology, the main causal agent is Streptococcus pyogenes, followed by Staphylococcus aureus and Escherichia coli. In most cases it is a polymicrobial infection, that is, by more than one bacterium.

This process is started by a trauma that allows bacteria to enter the superficial layers of the skin. These progress both horizontally and vertically to deeper layers and blood vessels, allowing the infection to spread throughout the body and become worse.

Depending on the patient's condition, different categories of necrotizing fasciitis can be distinguished. They are as follows:

  1. Healthy patient, afebrile.
  2. Feverish person sick-looking.
  3. Toxic-looking sick patient. This leads to confusion, tachycardia, and low blood pressure, among other clinical signs. In this category there is already a risk of losing a limb due to infection.
  4. Critically ill person at risk of losing his life. In this case, the patient experiences sepsis, a multi-organ failure caused by an inordinate immune response.

As indicated by the Centers for Disease Control and Prevention (CDC), the entry of bacteria can occur through multiple routes, beyond an injury. Consider burns, insect bites, and surgical procedures.

Risk factors for necrotizing fasciitis

The incidence of necrotizing fasciitis depends on the geographic region analyzed. The aforementioned source indicates that there are 0.4 cases per 100,000 people in the United States, while in Thailand this value increases to 7.45. Unfortunately, one of the biggest risk factors is living in poverty and in places with poor sanitary infrastructures.

Besides this, the average age of those affected is estimated to be 40 to 60 years, so being an adult or elderly could be considered a risk factor. People with diabetes, vascular disease or liver cirrhosis also show a certain predisposition to develop necrotizing fasciitis after injury.


As indicated by the professional portal MSDmanuals, diagnosis is made by blood culture, a culture of tissue from the lesions, a physical examination, an x-ray to reveal gas in the subcutaneous tissue, and other accessory tests. The main thing is to identify the causative agent in order to be able to fight it quickly.

Disinfection of wounds is essential to avoid necrotizing fasciitis, since the entry of bacteria is prevented.

Treatments available for necrotizing fasciitis

Unfortunately, up to 30% of patients with necrotizing fasciitis die. This percentage varies depending on the geographical area, ranging from 6% to 67%. Among the possible treatments we find the following:

  • Strong intravenous (IV) antibiotics: pathogenic bacteria must be fought as soon as possible, as they can cause death in a short time.
  • Surgery to open, drain the wound, and remove dead tissue: amputation of the entire affected limb is sometimes necessary.
  • Others: skin grafts, high pressure oxygen (hyperbaric oxygen therapy), and donor immunoglobulin transfusion.

Keep reading: Infectious cellulitis: causes and treatment

Wound cleaning is the only prevention

There is not much to say to end on a positive note, as necrotizing fasciitis can be easily aggravated, depending on the general health of the patient and the time of diagnosis. The only way to prevent it is to clean and disinfect any wound or scrape, no matter how small.

This infection is a race against the clock, as early diagnosis and proper treatment can literally save a patient's life. Unfortunately, in many low-income regions this is impossible and people with necrotizing fasciitis end up dying in half or more of the cases.

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