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Definition

Flesh-eating disease is more properly called necrotizing fasciitis, a rare condition in which bacteria destroy tissues underlying the skin. This tissue death, called necrosis or gangrene, spreads rapidly. This disease can be fatal in as little as 12 to 24 hours.

Description

Although the term is technically incorrect, flesh-eating disease is an apt descriptor: the infection appears to devour body tissue. Media reports increased in the middle and late 1990s, but the disease is not new. Hippocrates described it more than three millennia ago and thousands of reports exist from the Civil War. Approximately 500 to 1,500 cases of necrotizing fasciitis occur in the United States each year.

Flesh-eating disease is divided into two types. Type I is caused by anaerobic bacteria, with or without the presence of aerobic bacteria. Type II, also called hemolytic streptococcal gangrene, is caused by group A streptococci; other bacteria may or may not be present. The disease may also be called synergistic gangrene.

Type I fasciitis typically affects the trunk, abdomen, and genital area. For example, Fournier's gangrene is a "flesh-eating" disease in which the infection encompasses the external genitalia. The arms and legs are most often affected in type II fasciitis, but the infection may appear anywhere.

Causes and symptoms

The two most important factors in determining whether or not a person will develop flesh-eating disease are: the virulence (ability to cause disease) of the bacteria and the susceptibility (ability of a person's immune system to respond to infection) of the person who becomes infected with this bacteria.

In nearly every case of flesh-eating disease, a skin injury precedes the disease. As bacteria grow beneath the skin's surface, they produce toxins. These toxins destroy superficial fascia, subcutaneous fat, and deep fascia. In some cases, the overlying dermis and the underlying muscle are also affected.

Initially, the infected area appears red and swollen and feels hot. The area is extremely painful, which is a prominent feature of the disease. Over the course of hours or days, the skin may become blue-gray, and fluid-filled blisters may form. As nerves are destroyed the area becomes numb. An individual may go into shock and develop dangerously low blood pressure. Multiple organ failure may occur, quickly followed by death.

Diagnosis

The appearance of the skin, paired with pain and fever raises the possibility of flesh-eating disease. An x ray, magnetic resonance imaging (MRI), or computed tomography scans (CT scans) of the area reveals a feathery pattern in the tissue, caused by accumulating gas in the dying tissue. Necrosis is evident during exploratory surgery, during which samples are collected for bacterial identification.

Treatment

Rapid, aggressive medical treatment, specifically, antibiotic therapy and surgical debridement, is imperative. Antibiotics may include penicillin, an aminoglycoside or third-generation cephalosporin, and clindamycin or metronidazole. Analgesics are employed for pain control. During surgical debridement, dead tissue is stripped away. After surgery, patients are rigorously monitored for continued infection, shock, or other complications. If available, hyperbaric oxygen therapy has also be used.

Prognosis

Flesh-eating disease has a fatality rate of about 30%. Diabetes, arteriosclerosis, immunosuppression, kidney disease, malnutrition, and obesity are connected with a poor prognosis. Older individuals and intravenous drug users may also be at higher risk. The infection site also has a role. Survivors may require plastic surgery and may have to contend with permanent physical disability and psychological adjustment.

Prevention

Flesh-eating disease, which occurs very rarely, cannot be definitively prevented. The best ways to lower the risk of contracting flesh-eating disease are:

• take care to avoid any injury to the skin that may give the bacteria a place of entry
• when skin injuries do occur, they should be promptly washed and treated with an antibiotic ointment or spray
• people who have any skin injury should rigorously attempt to avoid people who are infected with streptococci bacteria, a bacteria that causes a simple strep throat in one person may cause flesh-eating disease in another
• have any areas of unexplained redness, pain, or swelling examined by a doctor, particularly if the affected area seems to be expanding

Key Terms

Aerobic bacteria

Bacteria that require oxygen to live and grow.

Anaerobic bacteria

Bacteria that require the absence of oxygen to live and grow.

CT scan (computed tomography scan)

Cross-sectional x rays of the body are compiled to create a three-dimensional image of the body's internal structures.

Debridement

Surgical procedure in which dead or dying tissue is removed.

Dermis

The deepest layer of skin.

Fascia, deep

A fibrous layer of tissue that envelopes muscles.

Fascia, superficial

A fibrous layer of tissue that lies between the deepest layer of skin and the subcutaneous fat.

Gangrene

An extensive area of dead tissue.

Hyperbaric oxygen therapy

A treatment in which the patient is placed in a chamber and breathes oxygen at higher-than-atmospheric pressure. This high-pressure oxygen stops bacteria from growing and, at high enough pressure, kills them.

Magnetic resonance imaging (MRI)

An imaging technique that uses a large circular magnet and radio waves to generate signals from atoms in the body. These signals are used to construct images of internal structures.

Necrosis

Abnormal death of cells, potentially caused by disease or infection.

Subcutaneous

Referring to the area beneath the skin.

For Your Information

Resources

Books

• Roemmele, Jacqueline A., Donna Batdorff, and Alan L. Bisno. Surviving the 'Flesh-Eating Bacteria': Understanding, Preventing, Treating, and Living With the Effects of Necrotizing Fascitis. New York: Avery Penguin Putnam, 2000.

• National Necrotizing Fascitis Foundation. PO Box 145, Niantic, CT 06357. (616) 261-2538.

This article was updated on 08-14-2006