Necrotizing fasciitis is a rare, and often fatal, infection by the bacterium Streptococcus pyogenes, also known as group-A streptococcus or GAS. Varieties of this bacterium also cause a wide range of other diseases, including strep throat, impetigo, cellulitis, erysipelas, scarlet fever, rheumatic fever, and more. To necrotize tissue is to kill it, and the word fasciitis signifies inflammation of the fascia, which are the thin sheaths of fibrous connective tissue that cover the muscles and other organs. In necrotizing fasciitis, group-A streptococci infect the deeper layers of the skin and the fascia in the tissue underneath the skin. Although this disease has often been referred to in the press as being caused by “flesh-eating bacteria,” GAS is not flesh-eating; that is, it does not actually eat away the flesh of victims of necrotizing fasciitis. Rather, GAS releases toxins that cause the body's own immune system to dissolve certain tissues. Necrotizing fasciitis first became popularly known in the 1990s. There was fear that it would become widespread, but it has remained rare. Necrotizing fasciitis is only one form of invasive group-A streptococcus infection. Other closely related forms include streptococcal toxic-shock syndrome (multi-organ infection) and bacteremia (infection of the blood).
The German-Austrian surgeon Christian Theodor Billroth (1829–1894) first described the streptococci bacterium. Billroth discovered Streptococcus pyogenes growing in infected wounds. The streptococci are gram-positive bacteria that tend to clump in pairs or chains and are classed into two basic types based on their ability to cause partial or complete hemolysis (breakdown of blood cells). Group A streptococci, which cause complete hemolysis, are further subdivided into a series of alphabetically labeled groups called Lancefield groups. In the 1930s, Rebecca Lancefield (1895–1981) defined the Lancefield groups using standard laboratory tests. She also showed that a protein in the GAS cell wall, M protein, is important to this bacterium's disease-causing power. Varying types of M protein can be used to distinguish over 120 different varieties of S. pyogenes, including those that cause necrotizing fasciitis.
Shifts in the M proteins and other substances produced by various strains of S. pyogenes are caused by genetic mutations and by genetic alterations caused by viruses (which can change the DNA of bacteria and other cells). Because of these changes, the virulence (tendency to cause disease) of various S. pyogenes strains waxes and wanes over time. During World War II (1939–1945), for example, there were reports of GAS bacteria causing toxic shock and destruction of tissue. These reports then abated until the late 1980s, when clusters of such infections began appearing in Australia, New Zealand, Scandinavia, and the central United States. A survey of four American states by the U.S. Centers for Disease Control and Prevention (CDC) conducted from 1989 to 1991 estimated that 10,000–15,000 invasive group A streptococcus infections were occurring in the U.S. each year. British tabloid writers coined the phrase “flesh-eating bacteria” to describe the new type of GAS infection. Necrotizing fasciitis has continued to occur at a more or less steady rate in the years since, neither disappearing nor becoming epidemic.
There are several types of life-threatening, invasive streptococcus A infections. Necrotizing fasciitis is a deep-seated infection of the tissues beneath the outer skin that destroys fascia and fat but may or may not destroy muscle and skin. It can be caused not only by S. pyogenes but, less commonly, by Clostridium perfringens or C. septicum. Necrotizing fasciitis may be caused by a blend of organisms in patients with diabetes or open wounds contaminated with fecal matter. An early term for the condition was “streptococcal gangrene.” Infections can begin at the site of a major or even invisible breakage of the skin. Typically, within 24 hours a lesion or sore spot appears at the wound site that is red, hot, and painful to the touch. There may also be fever. In the next 24–48 hours, the lesion becomes purple, violet, or blue, and blisters appear. Influenzalike symptoms occur in about 20% of cases, with symptoms including nausea, diarrhea, confusion, weakness, and tiredness. In three to four days gangrene may appear, with the entire limb, in some cases, appearing necrotic. The disease can cause death through shock, kidney failure, and respiratory arrest.
S. pyogenes is transmitted by direct contact or via airborne saliva droplets released by sneezing or coughing. Necrotizing fasciitis occurs when an appropriate strain of S. pyogenes enters a break in the skin. The break may be a large wound or a pinprick; in half of all cases, the break through which the pathogen entered cannot be identified.
Severe invasive group-A streptococcal disease, including necrotizing fasciitis, is primarily found in Europe and North America. In 2004, 3,833 cases of severe group A streptococcal disease were reported to the CDC.
Necrotizing fasciitis is treated with antibiotics, including penicillin, erythromycin, and clindamycin. In some cases, treatment may require amputation or other surgery to remove damaged tissue. Prompt care is essential. Without antibiotics, the death rate for invasive group-A streptococcus infection, including necrotizing fasciitis, is nearly 100%. Even with treatment the death rate is estimated by various experts at 25% to as much as 70%. In the 1990s, when public concern over this disease was at its height, Dr. Vincent Fischetti of Rockefeller University in New York advised the public that “If you see a rapidly progressing reddening area that is hot and quite sore to the touch and if you are running a fever, I would go to the doctor very quickly.”
WORDS TO KNOW
CLINICAL TRIALS: According to the National Institutes of Health, a clinical trial is “a research study to answer specific questions about vaccines or new therapies or new ways of using known treatments.” These studies allow researchers to determine whether new drugs or treatments are safe and effective. When conducted carefully, clinical trials can provide fast and safe answers to these questions.
FASCIA: Fascia is a type of connective tissue made up of a network of fibers. It is best thought of as being the packing material of the body. Fascia surrounds muscles, bones, and joints and lies between the layers of skin. It functions to hold these structures together, protecting these structures and defining the shape of the body. When surrounding a muscle, fascia helps prevent a contracting muscle from catching or causing excessive friction on neighboring muscles.
GANGRENE: Gangrene is the destruction of body tissue by a bacteria called Clostridium perfringens, or a combination of streptococci and staphylococci bacteria. C. perfringens is found widespread in soil and the intestinal tracts of humans and animals. It becomes dangerous only when its spores germinate, producing toxins and destructive enzymes, and germination occurs only in an anaerobic environment (one almost totally devoid of oxygen). While gangrene can develop in any part of the body, it is most common in fingers, toes, hands, feet, arms, and legs, the parts of the body most susceptible to restricted blood flow. Even a slight injury in such an area is at high risk of causing gangrene. Early treatment with antibiotics, such as penicillin, and surgery to remove the dead tissue will often reduce the need for amputation. If left untreated, gangrene results in amputation or death.
HEMOLYSIS: The destruction of blood cells, an abnormal rate of which may lead to lowered levels of these cells. For example, Hemolytic anemia is caused by destruction of red blood cells at a rate faster than which they can be produced.
M PROTEIN: M protein is an antibody found in unusually large amounts in the blood or urine of patients with multiple myeloma, a form of cancer that arises in the white blood cells that produce antibodies.
MUTATION: A mutation is a change in an organism's DNA that occurs over time and may render it less sensitive to drugs which are used against it.
NECROTIC: Necrotic tissue is dead tissue in an otherwise living body. Tissue death is called necrosis.
STREPTOCOCCUS: A genus of bacteria that includes species such as Streptococci pyogenes a species of bacteria that causes strep throat.
IN CONTEXT: TRENDS AND STATISTICS
The Division of Bacterial and Mycotic Diseases at Centers for Disease Control and Prevention (CDC) states that About 9,400 cases of invasive GAS disease occurred in the United States in 1999. Of these, about 300 were streptococcal toxic shock syndrome (STSS) and 600 were necrotizing fasciitis. In contrast, there are several million cases of strep throat and impetigo each year.
SOURCE: Centers for Disease Control and Prevention (CDC), Coordinating Center for Infectious Diseases, Division of Bacterial and Mycotic Diseases
Public consciousness of invasive group A streptococcal disease, including necrotizing fasciitis, has been out of proportion to the number of deaths it causes as compared to many other diseases and behaviors. Undoubtedly, one reason for this is the dramatic nature of the disease. A bacterial infection that “eats flesh” and has a 25–70% fatality rate even with the best medical care is certainly attention-getting. In addition, there have been a number of well-publicized deaths from the disease, including leading British economist David Walton (1963–2006), who died within 24 hours of diagnosis.
A vaccine for group-A streptococcus is being investigated, but remains elusive. According to the World Health Organization (WHO), clinical trials—experiments in human volunteers designed to test the vaccine's effectiveness and safety—are under way, but will probably take years to complete.
IN CONTEXT: REAL-WORLD RISKS
The Division of Bacterial and Mycotic Diseases at Centers for Disease Control and Prevention (CDC) states that “two of the most severe, but least common, forms of invasive GAS disease are necrotizing fasciitis and streptococcal toxic shock syndrome. Necrotizing fasciitis (occasionally described by the media as ‘the flesh-eating bacteria’) destroys muscles, fat, and skin tissue. Streptococcal toxic shock syndrome (STSS) causes blood pressure to drop rapidly and organs (e.g., kidney, liver, lungs) to fail. STSS is not the same as the ‘toxic shock syndrome’ frequently associated with tampon usage. About 20% of patients with necrotizing fasciitis, and more than half with STSS, die. About 10%–15% of patients with other forms of invasive group A streptococcal disease die.”
SOURCE: Centers for Disease Control and Prevention (CDC), Coordinating Center for Infectious Diseases, Division of Bacterial and Mycotic Diseases.
ICON Health Publications. Necrotizing Fasciitis. San Diego, CA: ICON Health Publications, 2004.
Factor, Stephanie H., et al. “Invasive Group A Streptococcal Disease: Risk Factors for Adults.” Emerging Infectious Diseases 9 (2003): 970–977.
Factor, Stephanie H., et al. “Risk Factors for Pediatric Invasive Group A Streptococcal Disease.” Emerging Infectious Diseases 11 (2005): 1062–1066.
Kolata, Gina. “A Dangerous Form of Strep Stirs Concern in Resurgence.” New York Times (June 8, 1994).
Musher, Daniel M., et al. “Trends in Bacteremic Infection Due to Streptococcus pyogenes (Group A Streptococcus), 1986–1995.” Emerging Infectious Diseases 2 (1996): 54–56.
Stevens, Dennis L. “Streptococcal Toxic-Shock Syndrome: Spectrum of Disease, Pathogenesis, and New Concepts in Treatment.” Emerging Infectious Diseases 1 (1995): 69–76.
National Institute of Allergy and Infectious Diseases. “Group A Streptococcal Infections.” November 2005. <http://www.niaid.nih.gov/factsheets/strep.htm> (accessed February 14, 2007).
National Necrotizing Fasciitis Foundation. “Home Page.” January 28, 2007. <http://www.nnff.org/> (accessed February 14, 2007).
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.
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.
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.
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.
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.
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
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. 〈http://www.nnff.org/〉.
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.
Flesh-eating disease is more properly called necrotizing fasciitis (pronounced nek-ro-TIZE-ing FASS-ee-i-tiss). The disease is caused by a rare bacterium that destroys tissues lying beneath the skin. The tissue death is called necrosis, or gangrene. It spreads very rapidly and can be fatal.
The term flesh-eating disease is not really correct. However, it does describe what seems to happen in the disease. An infection occurs that seems to consume body tissue. Reports about flesh-eating disease increased during the 1990s. But the disease has been known for a very long time. The Greek physician Hippocrates (c. 460–c. 377b.c.) described the condition more than two thousand years ago. The disease was also common during the Civil War (1861–65).
Flesh-eating disease affects the arms and legs most often, but the infection can occur anywhere on the body.
Flesh-Eating Disease: Words to Know
- Computed tomography (CT) scan:
- X rays taken of a portion of the body from various angles in order to obtain a three-dimensional picture of that region of the body.
- Computerized axial tomography (CAT) scan:
- Another name for a computed tomography (CT) scan.
- An extensive area of dead tissue.
- Abnormal death of tissues.
In nearly every case, flesh-eating disease begins with a skin infection. Bacteria begin to grow in the infected area. They release toxins (poisons) that destroy tissue under the skin.
Initially, the infected area appears red and swollen and feels hot. The area is extremely painful. After a few hours or days, the skin may become bluish-gray in color. Blisters filled with fluid may also form. The infected area becomes numb. An individual may go into shock and develop dangerously low blood pressure. The heart, kidneys, liver, and other organs may fail, leading to the patient's death.
Flesh-eating disease can often be diagnosed based on the way the skin looks, along with pain in the area and a fever. This diagnosis can be confirmed by a variety of tests, such as an X ray or a computed tomography (CT) scan. A CT scan is a procedure by which X rays are directed at a patient's body from various angles and the set of photographs thus obtained assembled by a computer program. This procedure is sometimes called a computerized axial tomography (CAT) scan. Samples of tissue under the skin can also be taken. Analysis of these samples will tell if the flesh-eating bacteria are present.
Two treatments are used with flesh-eating disease. One is the use of antibiotics. Antibiotics such as penicillin, a family of drugs known as aminoglycosides (pronounced uh-MEE-no-gly-ko-sides), or cephalosporins (pronounced seff-a-lo-SPORE-inz) are used to kill the flesh-eating bacteria. The second method of treatment is surgery on the infected area. During surgery, dead tissue is cut away so that healthy tissue can grow back. The patient is observed carefully after surgery to make sure that the infection does not return.
About 30 percent of those who are affected by flesh-eating disease eventually die of the infection. People with other disorders, such as diabetes (see diabetes mellitus entry), kidney disease, malnutrition, and obesity (see obesity entry), are at especially high risk for the disease. The elderly and intravenous drug users (those who inject drugs) are also at higher risk for the disease.
One consequence of the disease can be permanent scarring where the dead skin was cut away. Plastic surgery can sometimes be used to cover or reduce the amount of scarring.
There is no known method of preventing flesh-eating disease.
FOR MORE INFORMATION
Kotrappa, Kavitha S., Radhey S. Bansal, and Navin M. Amin. "Necrotizing Fasciitis." American Family Physician (May 1996): p. 1691.
Rth-Sahd, Lisa A., and Mary Pirrung. "The Infection that Eats Patients Alive." RN 1997 (March 1997): p. 28.
"The Flesh-eating Bacteria." Microbiology Home Page: Queen Mary Hospital. [Online] http://www.ha.org.hk/qmh/micro/strept.htm (accessed on October 19, 1999).
National Necrotizing Fasciitis Foundation Home Page. [Online] http://www.nnff.org/info.html (accessed on October 19, 1999).
Grant, Amy. "Streptococcus A–Necrotizing Fascitis." Bacterial Infections and Mycoses. [Online] http://www.emergency.com/strep-a.htm (accessed on October 19, 1999).