FAQ: Group A Streptococcus
» What is group A Streptococcus?
Group A Streptococcus (GAS) is a bacterium
commonly found in the throat and on the skin. Group A strep can
be present at these sites and cause no symptoms of disease, but
they may also cause infections that range from mild to severe
and some can even be life-threatening.
Most GAS infections are relatively mild illnesses, such as "strep
throat" or impetigo, a mild skin infection which is common
in children. Occasionally, however, these bacteria can reach parts
of the body where bacteria are not usually found, such as the
blood, deep muscle and fat tissue, or the lungs. When this happens
the infection is said to be invasive. Two of the most severe but
least common forms of invasive GAS disease are necrotizing
fasciitis and streptococcal
toxic shock syndrome. Necrotizing fasciitis (sometimes referred
to as "the flesh-eating disease") is a destructive infection of
muscle and fat tissue; streptococcal toxic shock syndrome is a
rapidly progressing infection, which causes septic shock and injury
to internal organs such as the kidneys, liver, and lungs.
» How are group A Streptococci
spread?
Group A streptococci are spread by direct contact with secretions
from the nose and throat of infected persons or by contact with
infected wounds or sores on the skin. The risk of spreading the
infection is highest when a person is ill, such as with "strep
throat" or an infected wound. Persons who carry the bacteria but
have no symptoms are much less contagious although they can pass
the bacteria to someone else. Treatment of infected persons with
an appropriate antibiotic for 24 hours or longer generally eliminates
their ability to spread the bacteria. Household items like plates,
cups, or toys probably do not play a major role in disease transmission.
» Why does invasive
group A streptococcal disease occur?
Invasive group A streptococcal infections occur when the bacteria
get past the defenses of the person who is infected. This may
occur when a person has sores or other breaks in the skin that
allow the bacteria to get into the tissue. Underlying health conditions
that decrease a person's immunity to infection also make invasive
forms of the disease more likely. In addition, certain strains
of group A streptococci are more likely to cause severe disease
than others.
» How common is invasive
group A streptococcal disease?
In Ontario, every year, approximately 2-3 people out of every
100,000 have an invasive GAS infection. Approximately 15% of these
cases have had streptococcal toxic shock while the number of people
with necrotizing fasciitis was 39 in 1998. This is much less than
the thousands of people who experience non-invasive infections
such as strep throat or impetigo each year.
» Who is most at
risk of getting invasive group A streptococcal disease?
Few people who come in contact with a virulent strain of GAS
will develop invasive GAS disease; many will have a routine throat
or skin infection, and most will have no symptoms whatsoever.
Although healthy people can get invasive GAS disease, those with
chronic illnesses like cancer, diabetes, and kidney disease requiring
dialysis and those who use medications such as steroids are at
higher risk. In addition, breaks in the skin, like cuts, wounds,
or chickenpox may provide an opportunity for the bacteria to enter
the body.
» What are the early
signs and symptoms of necrotizing fasciitis and streptococcal
toxic shock syndrome?
Early signs and symptoms of necrotizing fasciitis include fever,
severe pain (often out of proportion to other signs), swelling,
and redness at the wound site. Early signs and symptoms of streptococcal
toxic shock syndrome may include fever, dizziness, confusion,
diffuse red rash, and abdominal pain. Unfortunately, no sign or
symptom is specific only to streptococcal toxic shock syndrome,
making it sometimes difficult to differentiate from other illnesses.
» How is group
A streptococcal disease treated?
GAS infections can be treated with many different antibiotics.
Early treatment may reduce the risk of death in cases of invasive
disease, although even appropriate therapy does not prevent death
in every case. It is always important to complete the entire course
of antibiotics as prescribed.
» What can be done
to help prevent invasive group A streptococcal infections?
The spread of all types of GAS infections may
be reduced by good handwashing, especially after coughing and
sneezing, before preparing foods and before eating. Persons with
sore throats should be seen by a doctor who can perform tests
to find out whether it is "strep throat"; if so, the person should
stay home from work, school, or day care until 24 hours or more
after taking an antibiotic. All wounds should be kept clean and
watched for possible signs of infection: increasing redness, swelling,
drainage, and pain at the wound site. A person with signs of an
infected wound, especially if fever develops, should seek medical
care.
Because people who live in the same household as a person who
has necrotizing fasciitis or streptococcal toxic shock are at
higher risk of getting a similar infection, some public health
units or family physicians offer preventative antibiotics to contacts
of these severe cases. The Ministry of Health of Ontario has issued
recommendations for management and treatment of contacts of severe GAS cases.
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