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.

The most dangerous type of these infections is commonly known as "flesh-eating disease," and if untreated, it can cause death in a matter of hours.

Fortunately, such infections are extremely rare, but because they can quickly spread from the original infection site, it's important to know the symptoms. 

What causes necrotizing soft tissue infection?

Although some news stories use the phrase "flesh-eating bacteria," these infections can also be caused by a fungus. All types of bacteria and fungi can invade an open wound, even a small cut. Some studies suggest that people who have these severe infections may have more than one source of infection. One study showed that more than four types of bacteria were present in these wounds. Common causes include streptococcus bacteria, anaerobic Gram-positive cocci, the kind that causes strep throat (Streptococcus pyogenes), enterococci, Staphylococcus aureus, and Clostridium perfringens.

Wounds may be infected with more than one type of bacteria, and it can take time to find out which are present. For this reason, your health care 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 pathogens that cause necrotizing soft tissue infections can be passed from one person to another, so anyone can be infected. Those at greater risk are health care providers and others in contact with an infected person, and those with an open wound, even a small cut. Other risk factors include having peripheral artery disease, diabetes, obesity, and lifestyle habits such as alcoholism and injection drug use.

What are the symptoms of a necrotizing soft tissue infection?

The following are the most common symptoms of a necrotizing soft tissue infection. However, each person may experience symptoms differently. See your health care provider immediately 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 degrees Fahrenheit or 38 degrees Celsius) 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
  • Skin blisters, sometimes with a "crackling" sound under the skin
  • Pain from a skin wound that also has signs of a more severe infection, such as chills and fever
  • Grayish 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 weakened 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, alcoholism, 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 health care provider can see how far and how quickly it spreads outside the line.

The symptoms of a necrotizing soft tissue infection may resemble other medical conditions or problems. Always consult your health care provider for a diagnosis.

How is a necrotizing soft tissue infection diagnosed?

Your health care 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, if you've been exposed to slightly salty (brackish) water or saltwater, whether you've eaten raw seafood, and 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 health care 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 sampling

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 medication.

How is a necrotizing soft tissue infection treated?

Specific treatment for a necrotizing soft tissue infection will be determined by your health care provider based on the following:

  • The extent of the problem
  • Your age, overall health, and medical history
  • Your tolerance for specific medications, procedures, or therapies
  • Expectations for the course of the disorder
  • The opinion of the health care providers involved in your care
  • Your opinion and preference

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 medications 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 health care 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. People with diabetes or a weakened immune system should always check their feet and skin so that they can find and treat any small sores as soon as they appear, instead of letting them enlarge and become more vulnerable to infection.
  • Care for wounds and surgical sites carefully. Follow your health care 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. Even small cuts need to be cleaned with soap and water and be covered with an adhesive bandage.
  • Avoid sharing personal items such as 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. People who are at risk for these infections include those with peripheral artery disease, diabetes, obesity, and lifestyle habits such as alcoholism and injection drug use. Manage your risk factors to reduce the risk of infection.
  • See a health care provider immediately if you develop symptoms of the infection. 

Key points

  • 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, and 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 health care provider:

  • 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 names of new medicines, treatments, or tests, and any new instructions your provider gives you.
  • 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.