Necrotizing Fasciitis (Flesh-Eating Bacteria)

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What is necrotizing fasciitis?

Necrotizing fasciitis is an infection caused by bacteria. It can destroy skin, fat, and the tissue covering the muscles.

The disease sometimes is called "flesh-eating" bacteria. When it occurs on the genitals, it is called Fournier gangrene.

Necrotizing fasciitis is very rare but serious. About 3 out of 10 people who get this infection die from it.¹ Many people who get necrotizing fasciitis are in good health before they get the infection.²

Your risk of getting this infection is higher if you:

• Have a weak immune system.
• Have chronic health problems such as diabetes, cancer, or liver or kidney disease.
• Have cuts in your skin, including surgical wounds.
• 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. Some of these bacteria also cause infections such as strep throat and impetigo. Usually the infections caused by these bacteria are mild. But in rare cases they can cause a more dangerous infection.

You can get necrotizing fasciitis in:

• Wounds that come in contact with ocean water, raw saltwater fish, or raw oysters. You also can get it though injuries from handling sea animals such as crabs.
• Intestinal surgery, or tumors or gunshot injuries in the intestines.
• A muscle strain or bruise, even if there is no break in the skin.

Bacteria that cause necrotizing fasciitis can be passed from person to person through close contact, such as kissing, or by touching the wound of the infected person. But a person who gets infected by the bacteria is unlikely to get necrotizing fasciitis unless he or she has an open wound, chickenpox, or an impaired immune system.

What are the symptoms?

The symptoms often start suddenly. You may have:

• Pain from an injury that gets better over 24 to 36 hours and then suddenly gets worse. The pain may be much worse than you would expect from the size of the wound or injury.
• Skin that is red, swollen, and hot to the touch.
• A fever and chills.
• Nausea and vomiting.
• Diarrhea.

The infection may spread rapidly. It quickly can become life-threatening. You may go into shock and have tissue damage. Necrotizing fasciitis can lead to organ failure and death.

How is necrotizing fasciitis diagnosed?

The doctor will diagnose your infection based on how suddenly your symptoms started and how quickly the infection is spreading. The infected tissue may be tested for bacteria. You also may need X-rays, a CT scan, or an MRI to look for injury to your organs or to find out how much the infection has spread.

How is it treated?

You need medical care in a hospital right away. You may get care for shock, kidney failure, and breathing problems. You will get antibiotics to kill the bacteria. Most likely you will need surgery to stop the infection from spreading.

What if you have been near someone who has the disease?

Necrotizing fasciitis is very rare. Bacteria that cause the disease usually do not cause infection unless they enter the body through a cut or other break in the skin.

If you have been in close contact with someone who has necrotizing fasciitis, your doctor may give you an antibiotic to help reduce your chances of getting the infection.³ If you have any symptoms of an infection after you've been in close contact with someone who has necrotizing fasciitis, see your doctor right away.

Signs of infection include:

• Pain, swelling, warmth, or redness.
• Red streaks leading from a wound.
• Pus draining from a wound.
• Swollen lymph nodes in your neck, armpits, or groin.
• A fever.

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.

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.