Infection: Necrotizing Fasciitis
Infection: Necrotizing Fasciitis
Necrotizing fasciitis (NF) is a rare but potentially deadly infection of the deeper layers of the skin and the fascia, which is a sheet of connective tissue that overlies the muscles, bones, blood vessels, and internal organs. The fascia protects these parts of the body, provides them with structure, and acts as a shock absorber. Destruction of the fascia is dangerous because this sheet of tissue helps the body repair itself and acts as a protection against infection.
Necrotizing fasciitis is a life-threatening infection of the skin and fascia that develops when certain types of bacteria get into the body through breaks in the skin. These may be accidental cuts or scrapes or the result of surgery. “Flesh-eating bacteria” is a bit of a misnomer because the germs do not literally eat the soft tissue. Instead they secrete a substance that rapidly kills the tissue.
NF is particularly dangerous because it is often misdiagnosed until it is too late for the patient to survive. The early symptoms of necrotizing fasciitis often mimic the symptoms of influenza, a pulled muscle, or arthritis. In the case of necrotizing fasciitis following surgery, the patient's pain is often misdiagnosed as normal postoperative discomfort.
Necrotizing fasciitis was first reported in a medical publication in 1848. The Centers for Disease Control and Prevention (CDC) estimates that there are between 500 and 800 cases each year in the United States. Most affect adults; the average age of patients is between thirty-eight and forty-four years. Males are three times more likely to be affected. About half of all patients diagnosed with NF were previously strong and healthy.
Some people, however, are at greater risk of developing NF:
- People with diabetes, heart disease, and other disorders that affect blood circulation
- Drug addicts and alcoholics
- People with weakened immune systems, including those who have received organ transplants
- People with HIV infection
The cause of NF is infection by bacteria that enter the body through cuts or other breaks in the tissue, or infection of an incision after surgery. In some cases the injury may not even be apparent to the patient; one case in 2005 involved a firefighter who died from NF after spending several hours in bacteria-contaminated floodwaters rescuing trapped people. Most cases of NF involving injuries to the extremities are caused by Group A streptococci; these are sometimes called GAS infections. NF following surgery can be caused by a variety of other bacteria, sometimes several species at the same time.
A Survivor's Story
On Monday, June 12, 2006, I had what I thought to be a nasty bout of the flu…. By Wednesday evening I was vomiting every hour and could not catch my breath in between. I woke my husband and told him I think we better go to emergency…. We drove the 19 miles (30 kilometers) to our local hospital [in Canada] and I was admitted immediately. The original diagnosis was diabetic acid ketosis and after a week things had stabilized except for a persisting high temperature and a small lesion on the inside of my left groin. On June 21 I was told I would be transferred by ambulance to a major city'shospital (three hours away by car) for further testing….
The next day I fully remember is August 27, 2006. By 7:00 p.m. that night the hospital called my husband and told him he needed to come right now because I probably would not live…. I was only given a 30 percent chance of surviving and less than 5 percent chance I would keep my left leg. The necrotizing fasciitis had spread down my leg to the knee, across my back and up to my shoulder blades….
After sixteen surgeries I am happy to say that I have my leg, though severely damaged and extreme scarring from several skin grafting sites and skin donor sites. In total I spent six months in hospital, two and a half months in the intensive care unit and then transferred to a burn unit…. At the end of October 2006 I was finally transferred to a rehabilitation hospital where I was able to get the help to learn how to walk again. On December 6, 2006, I was able to come home. Once home I was only able to use a walker and wheelchair. By March I was walking with only the use of a cane and in April I had my last reconstructive surgery. My life has changed so much…. I can now almost do everything the way I used to. Walking will always be an issue but I am now able to drive and am back to work part-time.
Once in the body, the bacteria spread along the fascia, secreting toxins that destroy the fascia, the deeper layers of the skin, and muscle tissue. The toxins also prevent the flow of blood to the damaged tissue. As the infection spreads, the tissue reddens and swells. The speed of the spread depends on the depth of the infection within the fascia. Some doctors divide the symptoms of NF into three phases:
- Early (first twenty-four hours): Pain in the area of the cut or injury that quickly becomes more severe than would be expected; flu-like symptoms (diarrhea, nausea, vomiting, fever, confusion, dizziness, and weakness); rapid dehydration.
- Advanced (next three to four days): The affected body part swells and develops a purplish rash; blisters form and fill with a blackish fluid; the injured tissue starts to look decayed or dead (may be bluish or white).
- Critical (next two days): The person's blood pressure drops rapidly, the patient loses consciousness, and the entire body goes into toxic shock.
Doctors diagnose necrotizing fasciitis on the basis of the appearance of the injured tissue, the patient's other symptoms, and a blood test to identify the organism(s) causing the infection. In some cases the doctor can diagnose NF simply by passing a gloved hand between the tissue layers in the injured area; this procedure could not be done with healthy fascia. In some cases a surgeon may remove a small amount of the dying tissue for examination under a microscope. Treatment typically begins even before the bacterium is identified because speed of treatment is essential.
Patients with NF are given antibiotics intravenously, often a combination of two or three antibiotics to kill all the possible bacteria that may be involved in the infection. The patient is also examined by a surgeon, who will remove all the dead and infected tissue. This process is called debridement, and will be repeated until the surgeon is sure that all the infected tissue has been cut away. It is critical to remove this tissue to prevent the infection from spreading farther. In some cases the surgeon will have to amputate a limb to prevent death, and skin grafts may be necessary afterward.
Most patients will need to be monitored in an intensive care unit for several days or even several weeks. Some patients with NF are given additional treatment in a hyperbaric oxygen chamber. This is a special room in which the patient is treated with large amounts of oxygen.
The prognosis for necrotizing fasciitis depends on the promptness of treatment, the virulence (strength) of the organism causing the infection, and the patient's overall health. Without speedy treatment, between 70 and 75 percent of patients will die. The death rate is about 25 percent even in patients who were diagnosed quickly and treated at once.
Patients who survive may take months to years to recover completely. It is not unusual for people to require several operations, treatment in a burn center or other specialized hospital, a long period of rehabilitation, plastic surgery to restore normal appearance, and psychotherapy to deal with the depression that often follows NF.
There is no way to completely prevent NF. The best way to lower one's risk of NF is to keep the skin intact as much as possible and clean the skin thoroughly after a cut, scrape, or similar injury. Applying an antibacterial ointment to open cuts or sores also helps. Last, people who have strep throat should cover their mouth when they cough and dispose promptly of soiled tissues or handkerchiefs, as the bacterium that causes strep throat is a common cause of NF as well.
NF may become more common in the future, partly because there are more people with organ transplants, HIV infection, diabetes, and other conditions that put them at increased risk of NF.
SEE ALSO Staph infection; Strep throat; Toxic shock syndrome
WORDS TO KNOW
Debridement : The medical term for the surgical removal of dead or damaged soft tissue.
Fascia : A sheet of connective tissue that covers and binds together the muscles and other internal body structures.
Gangrene : Decay and death of soft tissue due to loss of blood supply.
Necrotizing : Causing the death of soft tissue.
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Tilden, Thomasine E. Lewis. Help! What's Eating My Flesh?: Runaway Staph and Strep Infections. New York: Franklin Watts, 2008.
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Munson, Jeff. “Tahoe Woman Battles Back a Year after Bout with Flesh-Eating Bacteria.” Tahoe Daily Tribune, April 13, 2008. Available online at http://news.rgj.com/apps/pbcs.dll/article?AID=2008804130352 (accessed April 18, 2008).
Centers for Disease Control and Prevention (CDC). Group A Streptococcal (GAS) Disease. http://www.cdc.gov/ncidod/dbmd/diseaseinfo/groupastreptococcal_g.htm (accessed April 17, 2008).
National Necrotizing Fasciitis Foundation (NNFF). What Is Necrotizing Fasciitis? Available online at http://www.nnff.org/nnff_what.htm (accessed April 18, 2008).