
Group A Streptococcal (GAS) Disease
(strep throat, necrotizing fasciitis, impetigo)
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What Is a "Flesh-Eating" Bacterial Infection?
Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: Jay W. Marks, MD, William C. Shiel Jr., MD, FACP, FACR
Media reports have popularized the term "flesh-eating
bacteria" to refer to a very rare but serious bacterial infection known as
necrotizing fasciitis. Necrotizing fasciitis is an infection that starts in the
tissues just below the skin and spreads along the flat layers of tissue (known
as fascia) that separate different layers of soft tissue, such as muscle and
fat. This dangerous infection is most common in the arms, legs, and abdominal
wall and is fatal in
30%-40% of cases.
Although necrotizing fasciitis may be caused by an
infection with one or more than one bacterium, in most cases the term
flesh-eating bacteria has been
applied to describe infections caused by the bacterium known as Streptococcus
pyogenes. The term flesh-eating has been used because the bacterial infection
produces toxins that destroy tissues such as muscles, skin, and fat.
Streptococcus pyogenes is a member of the group A streptococci, a group of bacteria that are responsible
for mild cases of sore throat (pharyngitis) and
skin infections, as well as rare, severe illnesses such as toxic shock syndrome
and necrotizing fasciitis. Most infections with group A streptococci result in
mild illness and may not even produce symptoms.
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What is group A streptococcus (GAS)?
Group A streptococcus is a bacterium often found in the
throat and on the skin. People may carry group A streptococci in the throat or
on the skin and have no symptoms of illness. Most GAS infections are relatively
mild illnesses such as "strep
throat," or impetigo. On rare occasions, these
bacteria can cause
other severe and even life-threatening diseases
How are group A streptococci spread?
These bacteria are spread through direct contact with
mucus from the nose or throat of persons who are infected or through contact
with infected wounds or sores on the skin. Ill persons, such as those who have
strep throat or skin infections, are most likely to spread the infection.
Persons who carry the bacteria but have no symptoms are much less contagious.
Treating an infected person with an antibiotic for 24 hours or longer generally eliminates their
ability to spread the bacteria. However, it is important to complete the entire
course of antibiotics as prescribed. It is not likely that household items like
plates, cups, or toys spread these bacteria.
What kind of illnesses are caused by group A streptococcal infection?
Infection with GAS can result in a range of symptoms:
Severe, sometimes life-threatening, GAS disease may occur
when bacteria get into parts of the body where bacteria usually are not found,
such as the blood, muscle, or the lungs. These infections are termed "invasive GAS disease." 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.
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| Picture of necrotizing fasciitis (flesh-eating disease) |
Next: How common is invasive group A streptococcal disease? »
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