Necrotizing Soft Tissue Infection

What is a necrotizing soft tissue infection?

A necrotizing soft tissue infection is a serious, life-threatening condition. It requires treatment right away to keep it from destroying skin, muscle, and other soft tissues. The word necrotizing comes from the Greek word "nekros." It means "corpse" or "dead." A necrotizing infection causes patches of tissue to die.

These infections are the result of bacteria invading the skin or the tissues under the skin. If untreated, they can cause death in hours.

Fortunately, such infections are very rare. They can quickly spread from the original infection site. So it's important to know the symptoms.

What causes a necrotizing soft tissue infection?

News stories often use the phrase "flesh-eating bacteria." But many types of bacteria can invade an open wound, even a small cut. Most commonly, a necrotizing infection is caused by a bacteria called Streptococcus. This is the same bacteria that causes strep throat. But many different types of bacteria can cause a necrotizing infection. Some of these are:

  • Enterococci
  • Staphylococcus aureus
  • Clostridium perfringens and other anaerobic bacteria
  • Gram negative bacteria such as Escherichia coli (E. coli)

It can take time to find out which bacteria are present. For this reason, your healthcare providers may recommend a broad-spectrum antibiotic. This treatment can fight many different infections. Delaying treatment raises your risk for a more serious problem.

Who is at risk for a necrotizing soft tissue infection?

The bacteria that cause necrotizing soft tissue infections are often introduced when a small cut or scrape becomes contaminated with soil or saliva. Anyone can be infected. People at greater risk are those with an open wound, even a small cut, especially if it has been in contact with dirt or bacteria in the mouth. Other risk factors are:

  • Peripheral artery disease
  • Diabetes
  • Obesity
  • Cancer
  • Heavy alcohol use
  • IV (intravenous) drug use

What are the symptoms of a necrotizing soft tissue infection?

These are the most common symptoms of a necrotizing soft tissue infection. See your healthcare provider right away if you have:

  • Pain that hurts more than you think it should, based on the size of the wound or sore
  • A wound with a fever (higher than 100.4°F or 38°C) and a rapid heartbeat. This is usually more than 100 beats a minute.
  • Pain that extends past the edge of the wound or visible infection
  • Pain, warmth, skin redness, or swelling at a wound, especially if the redness is spreading rapidly
  • Skin blisters, sometimes with a "crackling" sensation under the skin
  • Pain from a skin wound that also has signs of a more severe infection, such as chills and fever
  • Grayish, smelly liquid draining from the wound
  • A small sore or pus-filled bump that is unusually painful to the touch
  • An area around the sore that is hot to the touch
  • A hard time thinking clearly, especially along with one of the other symptoms noted
  • A lot of sweating, especially with one of the other symptoms noted
  • Areas of skin at or near a wound that feel numb
  • A sore that won't heal, especially if you:
    • Are obese
    • Have diabetes
    • Have a weak immune system from using a steroid regularly
    • Are on chemotherapy for cancer
    • Are on dialysis
    • Have peripheral artery disease
    • Drink a lot of alcohol
    • Have HIV/AIDS

People with some of these symptoms are surprised to learn that they have a necrotizing soft tissue infection. That's because it may not seem to be very severe at first. But these infections can worsen quickly if they are not aggressively treated. If you have a skin infection with a warm, red area, use a marker or pen to outline it. You and your healthcare provider can then see how far and how quickly it spreads outside the line.

The symptoms of a necrotizing soft tissue infection may look like other health problems. Always see your healthcare provider for a diagnosis.

How is a necrotizing soft tissue infection diagnosed?

Your healthcare provider will likely ask you about:

  • Your health and travel history
  • If you've recently been bitten by an animal or spider
  • If there was an injury to the affected area that was soiled or contaminated with saliva from the mouth or germs from elsewhere
  • If you've been exposed to slightly salty (brackish) water or saltwater
  • Whether you've eaten raw seafood
  • Whether you have a history of IV drug use

If you've developed a necrotizing soft tissue infection as a result of surgery, it may be slower moving. Your skin at the wound site may even look normal at first.

Because your healthcare provider may not be able to tell how far the infection has spread with only a physical exam, you may need other tests, such as:

  • Blood tests, including a complete blood cell count
  • X-rays to detect air in soft tissues
  • MRI scan
  • Tissue culture to determine which type of bacteria is present
  • Debridement of the area of concern to better inspect the tissue
  • Biopsy to send deeper tissue for cultures and to be looked at under a microscope

Your care team will check test results for unsuspected organisms. They will also look for bacteria that are hard to treat with the usual antibiotics. This may prompt a change in medicine.

How is a necrotizing soft tissue infection treated?

Treatment must be aggressive and started quickly to be effective. It might include most or all of these:

  • Removal of the infected tissue. This is to prevent the spread of the infection. The process is known as surgical debridement. Or it could even involve amputation of the limb that has the infection.
  • Antibiotics or antifungal treatments. These medicines fight the infection at its source.
  • Hyperbaric oxygen therapy. With this therapy, you will spend time in a pressurized chamber that raises the amount of oxygen available for you to breathe and for your red blood cells to take in. This is thought to help in wound healing.
  • Tetanus vaccine. Your healthcare provider might also recommend a tetanus shot to protect against more infection.

What are possible complications of a necrotizing soft tissue infection?

A necrotizing soft tissue infection can destroy skin, muscle, and other soft tissues. If untreated, it may lead to amputation of major parts of the body and sometimes death.

Can a necrotizing soft tissue infection be prevented?

To help prevent these infections:

  • Do foot checks and skin checks. If you have diabetes or a weak immune system, always check your feet and skin so that you can find and treat any small sores as soon as they appear. Do not let them get bigger and become more prone to infection.
  • Care for wounds and surgical sites carefully. Follow your healthcare provider's instructions when caring for wounds and surgical sites to prevent infection and keep the area clean.
  • Wash and cover small cuts and scrapes. Rigorously clean even small cuts with soap and water. Cover with an adhesive bandage.
  • Don't share personal items. This can include towels and razors.
  • Wash your hands regularly. This is especially important before preparing food, after coughing or sneezing, and after caring for people with strep throat or wounds from injury or surgery.
  • Know your risk factors. You are at higher risk for these infections if you have peripheral artery disease, diabetes, or are obese. Lifestyle habits such as heavy alcohol use and IV drug use can raise your risk, too. Manage your risk factors to reduce the risk of infection. For example, control your diabetes well. Or if you drink a lot, cut back on alcohol.
  • See a healthcare provider right away if you develop symptoms of the infection. 

Key points about a necrotizing soft tissue infection

  • A necrotizing soft tissue infection is a serious, life-threatening condition.
  • It can destroy skin, muscle, and other soft tissues.
  • A wound infection that is very painful, hot, draining a gray liquid, or accompanied by a high fever or other systemic symptoms needs care right away.
  • Treatment must be aggressive and started quickly to be effective. It may include surgery to remove the infected area.
  • Prevention includes caring for any cuts or sores right away.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
  • Ask if your condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if you do not take the medicine or have the test or procedure.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.
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