Necrotizing Soft Tissue Infection

What is necrotizing soft tissue infection?

A necrotizing soft tissue infection is a serious, life-threatening condition that requires immediate treatment to keep it from destroying skin, muscle, and other soft tissues. The word necrotizing comes from the Greek word "nekros", which 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 a matter of 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 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. Sometimes a necrotizing infection can be caused by a bacteria called Streptococcus, the same bacteria that causes strep throat. However, more often, many different types of bacteria are involved in a necrotizing infection including:
  • Enterococci
  • Staphylococcus aureus
  • Clostridium perfringens
  • Anaerobic and gram negative bacteria such as E. coli
It can take time to find out which bacteria are present. For this reason, your healthcare providers may recommend a treatment that can fight many different infections. Delaying treatment increases your risk for a more serious problem.

Who is at risk for necrotizing soft tissue infection?

The bacteria that cause necrotizing soft tissue infections are usually introduced when a small cut or scrape becomes contaminated with soil or saliva so anyone can be infected. Those 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 include having peripheral artery disease, diabetes, obesity, and lifestyle habits such as heavy alcohol use and injection 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 for any of these symptoms:

  • Pain that hurts more than you think it should, based on the size of the wound or sore 
  • A wound accompanied by a fever (higher than 100.4°F or 38°C) and a rapid heartbeat (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
  • Difficulty thinking clearly
  • Excessive sweating
  • Areas of skin at or near the wound that feel numb
  • A sore that won't heal, especially if you are obese, have diabetes, or have a weak immune system as a result of using a steroid regularly, if you are taking chemotherapy for cancer, if you are on dialysis, or if you have peripheral artery disease, heavy alcohol use, or HIV/AIDS

People with some of these symptoms are surprised to learn that they have a necrotizing soft tissue infection because it did not seem to be especially severe at first. But these infections can progress rapidly if they are not aggressively treated. If you have a skin infection with a warm, red area, you should use a marker or pen and outline the red area so that you and the healthcare provider can see how far and how quickly it spreads outside the line.

The symptoms of a necrotizing soft tissue infection may look like other medical conditions or 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 medical and travel history
  • If you've recently been bitten by an animal or spider
  • If there was an injury to the affected area which was soiled or contaminated with saliva from the mouth
  • If you've been exposed to slightly salty (brackish) water or saltwater
  • Whether you've eaten raw seafood
  • Whether you have a history of intravenous (IV) drug use

If you've developed a necrotizing soft tissue infection as a result of surgery, it may be slower moving and 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, he or she might order tests to get more information. These could include:

  • 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

Your medical team will check test results for unsuspected organisms and also for bacteria that are hard to treat with the usual antibiotics, which 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 the following:
  • Removal of the infected tissue. This is to prevent the spread of the infection. The process is known as surgical debridement.
  • 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 increases 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 immunization. Your healthcare provider might also recommend a tetanus shot to protect against additional infection.

What are the complications of a necrotizing soft tissue infection?

A necrotizing soft tissue infection can destroy skin, muscle, and other soft tissues, and, if untreated, lead to death.

Can a necrotizing soft tissue infection be prevented?

Your best approach to necrotizing soft tissue infections is to do your best to avoid them. 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 enlarge and become more vulnerable 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.
  • Avoid sharing 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 increased risk for these infections if you have peripheral artery disease, diabetes, are obese, or have lifestyle habits such as heavy alcohol use and injection drug use. Manage your risk factors to reduce the risk of infection.
  • See a healthcare provider immediately if you develop symptoms of the infection. 

Key points about 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 especially painful, hot, draining a gray liquid, or accompanied by a high fever, or other systemic symptoms needs immediate medical attention.
  • Treatment must be aggressive and started quickly to be effective.
  • Prevention includes immediately caring for any cuts or sores.

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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