Necrotizing Fasciitis Explained

Medically Reviewed By Lauren Castiello, MS, AGNP-C
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Necrotizing fasciitis, also called the “flesh-eating disease,” is a severe bacterial infection that usually develops due to a skin wound. “Necrotizing” refers to tissue death, while “fasciitis” refers to inflammation affecting the subcutaneous tissue called fascia. According to the Centers for Disease Control and Prevention (CDC), necrotizing fasciitis is rare. However, it may occur more commonly in people with weakened immune systems.

Read on to learn more about the causes, symptoms, treatments, and prevention methods for necrotizing fasciitis.

What are the causes of necrotizing fasciitis?

A man with a bandage on his leg
Oleg Breslavtsev/Getty Images

Necrotizing fasciitis results from bacteria entering the body, usually through breaks in the skin. These bacteria may enter the body through:

  • cuts or scratches
  • burns
  • insect bites
  • surgical procedures
  • drug injection sites

Some people may also develop necrotizing fasciitis through blunt trauma injuries that do not break the skin.

According to experts, Group A Streptococci are among the most common bacteria that cause the infection. The bacteria enter the body and spread, releasing toxins that disrupt blood flow to the subcutaneous tissues.

Inadequate blood flow means neither medical treatments nor the body’s infection-fighting cells can reach the affected area. As a result, the tissue begins to die.

What are the symptoms of necrotizing fasciitis?

The necrotizing fasciitis symptoms typically develop within 24 hours of an injury.

Initial symptoms may include:

The affected skin may look discolored and swollen. It may also be warm to the touch.

As the infection progresses, symptoms can include:

  • ulcers or black spots on the skin
  • further skin discoloration
  • pus or other discharge from the wound
  • fatigue

A fever over 104° F may be present in the infection’s advanced stages. Some people experience the opposite and develop a very low body temperature. As the nerves in the affected tissues begin to die, the pain may suddenly improve.

People with very advanced necrotizing fasciitis may become delirious or lose consciousness. Other symptoms of advanced infection can include decreased urination, low blood pressure, and rapid breathing and heart rate.

How do doctors diagnose necrotizing fasciitis?

To diagnose necrotizing fasciitis, doctors will typically begin by assessing your medical history and performing a physical examination.

Doctors may also perform a finger test by applying local anesthesia, making an incision in the affected skin, and pushing a finger into the tissue. The finger can push through the tissue without difficulty if the tissue is damaged.

In addition, doctors may run blood tests to assess a few different substance levels, including:

Elevated levels can indicate a necrotizing infection. Imaging tests such as CT scans can show the extent of inflammation and tissue damage.

A tissue biopsy and culture test can also help doctors determine the type of bacteria present. However, because the infection progresses so quickly, doctors may begin treatment before receiving the culture test results.

What are the treatments for necrotizing fasciitis?

Prompt treatment is critical for managing necrotizing fasciitis. Surgical debridement of the affected tissues and intravenous antibiotics are common initial treatments.

Even though the antibiotics may not be able to reach the infected area, they can still help prevent necrotizing fasciitis from spreading and may aid in controlling sepsis.

Doctors may continue antibiotic therapy until surgical debridement is no longer necessary and the signs of systemic inflammation are gone.

Because doctors may need to remove large areas of tissue, some people may require soft tissue reconstruction and skin grafts.

What is the outlook for people with necrotizing fasciitis?

Immediate treatment is critical to improving the outlook of people with necrotizing fasciitis. The CDC estimates that mortality rates for the infection may reach 25%.

Even with treatment, many people experience extended recovery periods with functional difficulties.

What are some potential complications for necrotizing fasciitis?

Necrotizing fasciitis can cause serious complications, including:

  • septic shock
  • toxic shock
  • extensive scarring
  • multiorgan failure
  • limb amputation
  • death

What are the risk factors for necrotizing fasciitis?

Several factors may increase your risk of contracting necrotizing fasciitis, including:

  • weakened immune system
  • diabetes
  • chronic illness
  • aspirin or nonsteroidal anti-inflammatory drug use
  • cancer
  • advanced age
  • obesity
  • the use of recreational drugs that require needles

Can you prevent necrotizing fasciitis?

Practicing good hygiene and properly caring for wounds can help prevent necrotizing fasciitis. Some beneficial practices include:

  • washing your hands frequently with soap and water
  • cleaning with soap and water any minor wound that breaks the skin
  • covering open or draining wounds with clean, dry bandages
  • contacting a doctor for deep or serious wounds

In addition, avoid submerging any open wounds in bodies of water. These include pools, hot tubs, or natural water sources like the ocean.

Other frequently asked questions

Here are a few other questions people commonly ask about necrotizing fasciitis. Lauren Castiello, MS, AGNP-C, has reviewed the answers.

Is necrotizing fasciitis contagious?

While the bacteria that cause necrotizing fasciitis can spread to other people, the CDC states that it is rare to pass on the infection to someone else.

Where is necrotizing fasciitis usually found?

Necrotizing fasciitis commonly develops in the lower leg area. However, it can also occur in the upper limbs, trunk, head, and neck.

How common is necrotizing fasciitis?

Researchers estimate that necrotizing fasciitis occurs at a rate of about 0.4 per 100,000 people annually in the United States. It is a rare but very serious infection.

What are the first signs of necrotizing fasciitis?

One of the characteristic early symptoms of necrotizing fasciitis is pain, which may occur at sites beyond the affected skin area. The skin can be discolored, swollen, and warm. Some people may also experience fever, dizziness, or excessive thirst.

Summary

Necrotizing fasciitis is a bacterial infection that can be life threatening. It develops when bacteria enter the body and impair blood flow to the affected area, causing tissues to die.

Prompt treatment is critical to limiting damage from the infection. Doctors typically surgically remove damaged or dead tissue while administering antibiotics to keep the infection from spreading.

Contact your doctor or seek immediate medical care if you have a skin wound and symptoms of an infection.

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Medical Reviewer: Lauren Castiello, MS, AGNP-C
Last Review Date: 2022 Sep 20
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