Necrotizing Fasciitis (Flesh-Eating Bacteria)

What is necrotizing fasciitis?

Necrotizing fasciitis is a rare bacterial infection that can destroy skin and the soft tissues beneath it, including fat and the tissue covering the muscles (fascia). Because these tissues often die rapidly, a person with necrotizing fasciitis is sometimes said to be infected with "flesh-eating" bacteria. The most common type of bacteria causing necrotizing fasciitis is Streptococcus pyogenes.

When necrotizing fasciitis occurs in the area of the genitals, it is called Fournier gangrene.

Necrotizing fasciitis is very rare but serious. Around 30% of those who develop necrotizing fasciitis die from the disease.¹

Many people who get necrotizing fasciitis are in good health prior to the infection.² Those at increased risk of developing the infection are people who:

• Have a weakened immune system or lack the proper antibodies to fight off the infection.
• Have chronic health problems such as diabetes, cancer, or liver or kidney disease.
• Have cuts, including surgical wounds from operations such as an episiotomy or a hernia repair.
• Recently had chickenpox or other viral infections that cause a rash.
• Use steroid medicines, which can lower the body's resistance to infection.

What causes necrotizing fasciitis?

Necrotizing fasciitis is caused by several kinds of bacteria. The most common cause is infection by a group A streptococcal (GAS) bacterium, most often Streptococcus pyogenes, which also causes other infections such as strep throat and impetigo. Usually the infections caused by these bacteria are mild. But in rare cases the bacteria produce poisons (toxins) that can damage the soft tissue below the skin and cause a more dangerous infection that can spread quickly along the tissue covering the muscle (fascia). The bacteria also can travel through the blood to the lungs and other organs. The disease also may be caused by Vibrio vulnificus. Infection with this bacterium can occur if wounds are exposed to ocean water or contact raw saltwater fish or oysters. Infection also may occur through injuries from handling sea animals such as crabs. These infections are more common in people who have chronic liver diseases such as cirrhosis.

Another type of necrotizing fasciitis may be caused by multiple bacteria found in the intestine. This type most often affects people with diabetes or peripheral arterial disease. Sometimes people who have gunshot injuries, intestinal surgery, or tumors in the lower digestive tract develop necrotizing fasciitis.

A break in the skin allows bacteria to infect the soft tissue. In some cases, infection can also occur at the site of a muscle strain or bruise, even if there is no break in the skin. It may not be obvious where the infection started, because the bacteria may travel through the bloodstream to other parts of the body.

Group A strep bacteria producing the toxins that cause necrotizing fasciitis can be passed from person to person. But a person who gets infected by the bacteria is unlikely to develop a severe infection unless he or she has an open wound, chickenpox, or an impaired immune system.

What are the symptoms?

A person may have pain from an injury that gets better over 24 to 36 hours and then suddenly gets worse. Often the pain is much worse than would be expected from the size of the wound or injury. Other symptoms may include fever, chills, and nausea and vomiting or diarrhea. The skin usually becomes red, swollen, and hot to the touch. If the infection is deep in the tissue, these signs of inflammation may not develop right away.

The symptoms often start suddenly (over a few hours or a day), and the infection may spread rapidly and can quickly become life-threatening. Serious illness and shock can develop in addition to tissue damage. Necrotizing fasciitis can lead to organ failure and, sometimes, death.

How is necrotizing fasciitis diagnosed?

A person with necrotizing fasciitis usually is very sick before he or she sees a doctor. The doctor may suspect necrotizing fasciitis based on how fast the symptoms developed and how quickly the infection is progressing. A sample of the infected tissue may be taken to identify the type of bacteria causing the infection. X-rays, CT scans, or MRI scans may be done to look for injury to the organs or to find out the extent and depth of the infection.

How is it treated?

Immediate medical care in a hospital is always necessary. Supportive care for shock, kidney failure, and breathing problems is often needed. Most people will need surgery to stop the infection from spreading. Extensive use of antibiotics is needed to kill the bacteria.

What if I know someone with the disease?

Most people will not get necrotizing fasciitis. You generally do not have to worry about getting the disease, because the bacteria that cause the disease usually do not cause infection unless they enter the body through a cut or other break in the skin.

In very rare cases, the bacteria can be spread from one person to another through close contact such as kissing. People who live or sleep in the same household with an infected person or who have direct contact with the mouth, nose, or pus from a wound of someone with necrotizing fasciitis have a greater risk of becoming infected.

If you have been in close personal contact with someone who develops necrotizing fasciitis, there is a small chance that your doctor may recommend that you take an antibiotic to help reduce your chances of getting an infection.³ If you do develop any symptoms of an infection after being in close contact with someone who has necrotizing fasciitis, see your doctor right away.

To help prevent any kind of infection, wash your hands often, and always keep cuts, scrapes, burns, sores, and bites clean.

Frequently Asked Questions

Symptoms of necrotizing fasciitis may develop quickly, often as soon as 24 hours after a minor skin injury. The rapid onset of symptoms is one of the most important clues that you may need immediate medical care. Another common feature of this disease is pain that is greater than you would expect from the wound or injury.

Necrotizing fasciitis most commonly affects extremities, particularly the legs, but can affect any part of the body. When necrotizing fasciitis occurs in the area of the genitals, it is called Fournier gangrene.

The most common early symptoms include:

• Sudden, severe pain in the affected area.
• Fever, nausea, vomiting, fatigue, and other flu-like symptoms.
• Redness, heat, swelling, or fluid-filled blisters in the skin over the affected area. If the infection is deep in the tissue, these signs of inflammation may not develop right away.

Later symptoms may include:

• Signs of shock (including confusion, fainting, or dizziness), which are often worse when you get up from sitting or lying down. These symptoms are caused by a drop in blood pressure.
• Scaling, peeling, or discolored skin over the affected area, which are signs of tissue death, or gangrene.

A common entry point for the bacteria is through a wound such as a burn, cut, scrape, or insect bite. Within 24 hours after the bacteria have entered the wound, swelling, heat, redness, and tenderness spread quickly from the original wound site. Within 24 to 48 hours after spreading, the redness may darken to purple and then to blue. Blisters containing yellow fluid may also form. Within 4 to 5 days after the initial infection, gangrene develops. Within 7 to 10 days, dead skin separates from healthy skin as the infection continues to spread into other tissue. Certain strains of bacteria (such as streptococci) can be more aggressive, shortening the entire process to 2 to 4 days.

A person with necrotizing fasciitis usually is very sick by the time he or she sees a doctor. The person is likely to need immediate treatment—for shock or organ failure—before any test results are available.

Tests used to evaluate a person with possible necrotizing fasciitis may include:

• Routine blood tests, such as complete blood count (CBC), blood chemistry, creatine phosphokinase (CPK), and C-reactive protein. Test results can help show whether an infection is present or if muscles deep in the body have been damaged.
• Skin and wound cultures, which are often obtained during surgery, to determine what kind of bacteria are causing the infection. Fluid and material from the wound can be stained with special chemicals or dyes to quickly identify the type of bacteria.
• Chest X-rays, to look for signs of lung damage (respiratory distress syndrome).
• Other X-rays, to check for gas or fluid buildup at the site of the infection.

A CT scan or magnetic resonance imaging (MRI) is sometimes done when the diagnosis is uncertain or to help determine the depth of the infection.

If necrotizing fasciitis is suspected, surgical removal of the infected tissue is usually necessary both to confirm the diagnosis and to stop the spread of infection.

The person may need other tests, depending on the part of the body affected by the infection and what problems it is causing.

A person with necrotizing fasciitis needs to go to the hospital for treatment as soon as the condition is suspected. The person will usually be treated in the intensive care unit (ICU).

Early treatment of necrotizing fasciitis is critical. The sooner treatment begins, the more likely the person will recover from the infection and avoid serious consequences, such as limb amputation or death.

Treatment may include:

• Surgery that removes infected tissue and fluids to stop the spread of infection.
• Medicines (antibiotics and intravenous immunoglobulin) to kill the bacteria causing the infection.
• Procedures to treat complications such as shock, respiratory problems, and organ failure.
• Hyperbaric oxygen therapy, which can help prevent tissue death and promote healing.

Surgery

Surgery (surgical debridement) is almost always needed to remove the infected dead tissue resulting from necrotizing fasciitis. This can also reduce the number of bacteria in the body, remove toxins, and stop the spread of infection. Most people need several operations to fully control the infection.

Removing limbs (amputation) or organs may be necessary to save the person's life, depending on how severe the infection is and where it has spread.

Medications

Intravenous (IV) antibiotics such as clindamycin and penicillin are used to kill some kinds of bacteria that can cause necrotizing fasciitis (usually streptococci and staphylococci) and stop the production of toxins that cause the illness. More than one antibiotic (broad-spectrum therapy) may be needed, especially when the person has diabetes or injury to the intestines.

Intravenous immunoglobulin (IVIG) may be used along with surgery and antibiotics to help treat necrotizing fasciitis. IVIG boosts the body's immune system and reduces the effects of bacterial toxins. It is not yet clear whether treatment with IVIG helps cure necrotizing fasciitis.

Oxygen therapy

Hyperbaric oxygen therapy, which provides your body with high levels of oxygen, may help control infection, promote healing, and reduce the need for surgery.^{4, 5} For this treatment, the person with necrotizing fasciitis is placed in a chamber and the air in the chamber is enriched with oxygen. Hyperbaric oxygen therapy is not routinely done to treat necrotizing fasciitis.

Treatment for complications

Other types of treatment for complications caused by necrotizing fasciitis may be needed. The kind of treatment depends on what part of the body is affected and what problems the infection is causing.

Shock, kidney failure, and breathing problems caused by damage to the lungs (respiratory distress syndrome) are the most common complications of necrotizing fasciitis. Many people who develop necrotizing fasciitis will need dialysis to treat kidney failure, and about one-half will need a machine (ventilator) to help with breathing until their health improves.

A person with necrotizing fasciitis needs prompt medical attention in a hospital. Seek medical treatment immediately if you develop symptoms of this illness. About 3 in 10 people (30%) who develop necrotizing fasciitis die from the infection.¹ Early treatment is critical for successful recovery.

Prevention

Necrotizing fasciitis is a rare type of infection. Experts do not know exactly why bacteria that usually cause more mild diseases, such as strep throat or impetigo, also can cause a severe infection such as necrotizing fasciitis.

Necrotizing fasciitis usually occurs when the bacteria enter the body through a cut or sore. In very rare cases, the bacteria can be spread from one person to another through close contact such as kissing. People who live with an infected person or who touch the mouth, nose, or pus from a wound of someone with necrotizing fasciitis have a greater risk of becoming infected.

If you have been in close personal contact with someone who develops necrotizing fasciitis, your doctor may recommend that you take an antibiotic medicine to help reduce your chances of getting an infection. ³ If you do develop any symptoms of an infection after being in close contact with someone who has necrotizing fasciitis, see your doctor right away.

Most people who get necrotizing fasciitis are in good health before they become infected. You can lower your risk of infection if you:

• Wash your hands often.
• Keep all wounds clean. This includes cuts, scrapes, burns, sores caused by chickenpox or shingles, insect or animal bites, and surgical wounds.
• Watch for signs of infection, such as increased pain, swelling, pus, heat, or redness near the wound or fever of 100°F (37.78°C) or higher with no other obvious cause. If signs of infection appear, seek medical attention promptly.
• If you recently strained a muscle or sprained a joint and develop fever, chills, and severe pain, seek medical care immediately. These may be signs of deep soft tissue infection.
• If you have severe pain, swelling, and fever, do not treat yourself with nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen. If you have developed a soft tissue infection, these drugs may temporarily reduce the symptoms without treating the infection and may delay how quickly you seek proper medical care.

Online Resource

Citations

1. Tan JS (2007). Necrotizing skin and soft-tissue infections. In RE Rakel, ET Bope, eds., Conn's Current Therapy, pp. 95–99. Philadelphia: Saunders Elsevier.

2. Stevens DL (1999). The flesh-eating bacterium: What's next? Journal of Infectious Diseases, 179(Suppl 2): S366–S374.

3. Centers for Disease Control and Prevention (2004). Group A Streptococcal (GAS) Disease. Available online: http://www.cdc.gov/ncidod/dbmd/diseaseinfo/groupastreptococcal_g.htm.

4. Swartz MN, Pasternack MS (2005). Necrotizing fasciitis section of Skin and soft tissue infections. In GL Mandell et al., eds., Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 6th ed., vol. 1, pp. 1189–1191. Philadelphia: Elsevier.

5. Wilkinson D, Doolette D (2004). Hyperbaric oxygen treatment and survival from necrotizing soft tissue infection. Archives of Surgery, 139(12): 1339–1345.

Other Works Consulted

• Nichols RL (2007). Bacterial diseases of the skin. In RE Rakel, ET Bope, eds., Conn's Current Therapy, pp. 971–976. Philadelphia: Saunders Elsevier.