What is necrotizing fasciitis?

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

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 1 out of 4 people who get this infection die from it.¹ Many people who get necrotizing fasciitis are in good health before they get the infection.

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 when bacteria enter a wound, such as from an insect bite, a burn, or a cut. You can also get it in:

• Wounds that come in contact with ocean water, raw saltwater fish, or raw oysters, including injuries from handling sea animals such as crabs.
• An intestinal surgery site, or in tumors or gunshot injuries in the intestines.
• A muscle strain or bruise, even if there is no break in the skin.

The bacteria that cause necrotizing fasciitis can be passed from person to person through close contact, such as touching the wound of the infected person. But this rarely happens unless the person who is exposed to the bacteria has an open wound, chickenpox, or an impaired immune system.

What are the symptoms?

The symptoms often start suddenly after an injury. You may need medical care right away if you have pain 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. You may also have:

• 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 damage to skin, fat, and the tissue covering the muscles. (This damage is called gangrene.) 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.