What Is Necrotizing Fasciitis?

Necrotizing fasciitis is a rare but potentially fatal kind of bacterial infection. It also sometimes goes by the scary name, "flesh eating disease." Fascia is the soft tissue that interweaves around your organs and muscles. When this becomes infected, it’s called “fasciitis.” The term “necrotizing” means death, so “necrotizing fasciitis” refers to the death of tissues from an infection of your fascia. 

Necrotizing fasciitis can cause swelling and redness in an affected area, as well as extreme pain. It can also lead to life-threatening complications such as sepsis. It needs to be quickly diagnosed and immediately treated with intravenous antibiotics and surgery to remove the infected tissue.  

Necrotizing fasciitis is rare, affecting roughly between 2-4 people per million each year in the United States. People with certain medical conditions, like diabetes, are at higher risk.

Types

Sometimes people distinguish necrotizing fasciitis based on the part of the body affected. For example, Fournier’s gangrene is a term for necrotizing fasciitis that affects the areas around your reproductive organs and your anus. Sometimes it affects your extremities or the area around your abdomen instead.

Scientists also make distinctions based on the type of organisms causing the infection. People with types II, III, and IV tend to have more aggressive disease and higher mortality rates compared to Type I.

Type I 

This type describes 70%-80% of infections. It is usually caused by simultaneous infection with more than one bacteria type. This might include Pseudomonas bacteria, E. coli, or many other species. 

Type II

In contrast from type I, type II necrotizing fasciitis infections, found in 20%-30% of people, are usually caused by a single bacteria type. Typically, this is Streptococcus pyogenes (the bacteria that also causes strep throat). Less commonly, Staphylococcus aureus (“staph”) is the cause.

Type III

Type III necrotizing fasciitis is much less common in the United State. It is caused by marine-related organisms, so you might get it by eating contaminated seafood or having a wound exposed to contaminated water.

Type IV

Type IV is caused not by bacteria, but by fungal infections. It's rare, and it usually only happens in people who have underlying problems with their immune system.

Necrotizing Fasciitis Symptoms

The symptoms of necrotizing fasciitis usually escalate quickly. 

Initial Symptoms

Most people will first have swelling, warmth, and redness over an area of skin that spreads quickly. Fever may also be present.

A very critical initial symptom is severe pain. This pain may extend past the area that appears red and swollen. The pain is often much more intense than that of other, more common, types of infections.

If you start to have these symptoms after an injury, a procedure, or surgery, you should seek immediate medical attention. 

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Later Symptoms 

After these initial symptoms, the situation may worsen. These later symptoms might include:

• Ulcers or black spots on the skin
• Large blisters on the skin, which might ooze pus
• Worsening swelling, even outside of the red area
• Reduced sensation of the affected area
• Dizziness
• Nausea or diarrhea

Especially if not diagnosed and treated promptly, necrotizing fasciitis can ultimately lead to symptoms from complications of the disease such as sepsis, an extreme and life-threatening immune response to an infection.

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Causes

Necrotizing fasciitis usually happens after the skin is broken in some way, allowing bacteria to enter the body and the fascia. For example, it might happen soon after a cut, an animal bite, a medical procedure like an injection, or after surgery. It’s more likely if a wound wasn’t properly cleaned and disinfected.

After initial infection, the bacteria spread along the planes of fascia that intertwine around different parts of the body. The infection starts releasing toxins which ultimately causes small blood vessels to be blocked, leading to tissue death. 

Necrotizing fasciitis can be spread from person to person, although this is extremely rare. In order to contract necrotizing fasciitis from someone who has it, you would need to have direct contact with their open wound. The bacteria they pass on would also have to enter your body, which can happen if you have an open wound as well.

Risk Factors

Different factors can increase your risk of getting necrotizing fasciitis. Some of these include the following:

• Diabetes
• Alcohol use disorder
• Severe liver or kidney disease
• Cancer
• Malnutrition
• Having a disorder or taking a medication that suppresses your immune system
• Advanced age

However, some people get very serious cases of necrotizing fasciitis even if they don’t have any of these risk factors.

Diagnosis

It’s important that necrotizing fasciitis be diagnosed as quickly as possible, so that the correct treatment can begin. This gives the best chance of minimizing complications and surviving the infection. 

Unfortunately, it is often difficult for healthcare providers to initially distinguish necrotizing fasciitis from a more common but generally less serious infection, cellulitis (infection of the skin). Severe pain and more severe skin changes can give clues, as can signs of complications, like very low blood pressure.

There is not a single test that can be used to diagnose necrotizing fasciitis. However, some blood tests might give clues that necrotizing fasciitis is a possibility. Some examples are:

• C-reactive protein, which might show signs of inflammation.
• Complete blood cell count, which might show signs of infection.
• Complete metabolic panel, blood clotting studies, or lactate levels, which might give clues about complications from necrotizing fasciitis.

Imaging tests such as CT (computed tomography) can also sometimes be helpful for diagnosis. However, often it is important for health professionals not to wait on imaging to make the diagnosis but instead move forward with treatment. Surgery is the only definitive way to diagnose necrotizing fasciitis.

Once it’s clear that this is the diagnosis, it’s also helpful to get blood culture tests. Technicians can use a blood sample or a sample of infected tissue to find out exactly which bacteria are causing the infection. That helps determine the best antibiotic treatment.

Treatments for Necrotizing Fasciitis

Antibiotics and surgery are the two primary treatment options for necrotizing fasciitis.

Antibiotics

Antibiotic treatment to kill the bacteria should begin as soon as possible after diagnosis. This will be through an intravenous line, to get the antibiotics spread through your body more quickly. 

It is likely that the antibiotic prescribed will be one that can treat a wide range of infections, because your healthcare provider won’t initially know the exact bacteria causing the infection. One or more of the following antibiotics might be part of treatment:

• Firvanq (vancomycin)
• Zyvox (linezolid)
• Zosyn (piperacillin-tazobactam)
• Rocephin (ceftriaxone)
• Flagyl (metronidazole)
• Cleocin (clindamycin)

After the results of bacterial culture are available, your healthcare provider may shift you to a different antibiotic that is more specifically targeted to your infection.

Surgery

Although antibiotics are a critical part of treating necrotizing fasciitis, prompt surgery to remove affected tissue is still required. Anyone with necrotizing fasciitis should receive surgery within 12 to 15 hours of admission to a hospital; death rates can be nine times higher in people who have surgery 24 hours after their symptoms start.

The nature of this surgery varies based on the specific areas of the body affected and their severity. For example, someone with a severe case of necrotizing fasciitis affecting their leg might need an amputation, but not every surgery needs to be that extreme. 

Most people need multiple surgeries spread out over several days. That’s the best way to ensure that all the infected and dead tissue is completely removed while still saving as much healthy tissue as possible. Additional reconstructive or cosmetic surgery may also be needed in some cases.

Additional Management

Some people with necrotizing fasciitis are critically ill and need care in an intensive care unit (ICU). Many may also need additional supportive treatments. Some examples might include:

• Intravenous (IV) fluids, to treat low blood pressure and correct imbalances in electrolytes (charged particles) in the blood
• Medications to increase blood pressure
• Medications to treat pain

Sometimes less established treatment approaches are available to help with necrotizing fasciitis. This might include intravenous immunoglobulin G (a mixture of antibodies) or hyperbaric (high pressure) oxygen. 

Prevention

We don’t have vaccines to prevent necrotizing fasciitis. But the following may help you reduce your risk.

• Wash your hands with soap and water frequently, especially after you use the bathroom.
• Clean all cuts and injuries that break the skin using soap and water. After cleaning, cover any open wounds with a dry bandage until they heal. Replace the bandage if it becomes soiled.
• See a healthcare professional for any serious wound or any wound you can't clean well. 
• If you have an open wound, avoid hot tubs, swimming pools, or natural bodies of water until it heals. 
• If you have diabetes, use warm soapy water on your feet every day. Check for any cuts as well, and bandage if needed.
• Care for any other conditions that can increase the risk of skin drying and cracking (e.g., foot fungal infections). 

Complications

The most important complication of necrotizing fasciitis is sepsis, an overwhelming dangerous immune response to an infection. Even with treatment, sepsis sometimes turns into septic shock, which causes very low blood pressure. It can also trigger increased blood clots and increased bleeding. 

All of this can damage various organs, such as your kidneys. Depending on the severity of the situation and the promptness of treatment, some people die, even those who’ve received high quality medical attention. 

In some cases, organ damage is permanent in those who survive. For example, you might have some degree of permanent kidney damage after the experience. In other cases, you might fully recover, although this takes time.

Other people have complications directly related to the infection and surgery. For example, if your leg needs to be amputated, you might need a prosthetic leg and physical therapy.

A Quick Review

Necrotizing fasciitis is a very serious type of infection of the fascia, part of your body’s connective tissue. It can spread rapidly through the fascia tissue, killing cells as it spreads.

It’s critical to seek medical attention right away if you have redness, swelling, and intense pain in an area after an injury, cut, or a medical procedure. Although it can be difficult to diagnose at first, it’s critical that antibiotics and surgical treatment begin as quickly as possible.

Recovery can take a while. Some people have residual organ damage or permanent changes from their surgeries. It will take some time to get back your strength and stamina.