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Group A Streptococcal (GAS) Disease
(strep throat, necrotizing fasciitis, impetigo)

Frequently Asked Questions

bulleted list item, level 1 What is group A Streptococcus (GAS)?
bulleted list item, level 1 How are group A streptococci spread?
bulleted list item, level 1 What kind of illnesses are caused by group A streptococcal infection?
bulleted list item, level 1 How common is invasive group A streptococcal disease?
bulleted list item, level 1 Why does invasive group A streptococcal disease occur?
bulleted list item, level 1 Who is most at risk for getting invasive group A streptococcal disease?
bulleted list item, level 1 What are the early signs and symptoms of necrotizing fasciitis and streptococcal toxic shock syndrome?
bulleted list item, level 1 How is invasive group A streptococcal disease treated?
bulleted list item, level 1 What can be done to help prevent group A streptococcal infections?

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. Occasionally these bacteria can cause severe and even life-threatening diseases.

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") is a rapidly progressive disease which destroys muscles, fat, and skin tissue. Streptococcal toxic shock syndrome (STSS) results in a rapid drop in blood pressure and organs (e.g., kidney, liver, lungs) to fail. STSS is not the same as the "toxic shock syndrome" due to the bacteria Staphylococcus aureus which has been associated with tampon usage. While 10%-15% of patients with invasive group A streptococcal disease die from their infection, approximately 25% of patients with necrotizing fasciitis and more than 35% with STSS die.

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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.

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What kind of illnesses are caused by group A streptococcal infection?

Infection with GAS can result in a range of symptoms:

"" bulleted list item, level 2 No illness
  bulleted list item, level 2 Mild illness (strep throat or a skin infection such as impetigo)
  bulleted list item, level 2 Severe illness (necrotizing faciitis, streptococcal toxic shock syndrome)

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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How common is invasive group A streptococcal disease?

About 9,000-11,500 cases of invasive GAS disease occur each year in the United States, resulting in 1,000-1,800 deaths annually. STSS and necrotizing fasciitis each comprise an average of about 6%-7% of these invasive cases. In contrast, there are several million cases of strep throat and impetigo each year.

Why does invasive group A streptococcal disease occur?

Invasive GAS 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, or when the person’s ability to fight off the infection is decreased because of chronic illness or an illness that affects the immune system. Also, some virulent strains of GAS are more likely to cause severe disease than others.

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Who is most at risk of getting invasive group A streptococcal disease?

Few people who come in contact with GAS will develop invasive GAS disease. Most people will have a throat or skin infection, and some may have no symptoms at all. Although healthy people can get invasive GAS disease, people with chronic illnesses like cancer, diabetes, and chronic heart or lung disease, and those who use medications such as steroids have a higher risk. Persons with skin lesions (such as cuts, chicken pox, surgical wounds), the elderly, and adults with a history of alcohol abuse or injection drug use also have a higher risk for disease.

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What are the early signs and symptoms of necrotizing fasciitis and streptococcal toxic shock syndrome?

Early signs and symptoms of necrotizing fasciitis;

"" bulleted list item, level 2 Severe pain and swelling, often rapidly increasing
  bulleted list item, level 2 Fever
  bulleted list item, level 2 Redness at a wound site

Early signs and symptoms of STSS;

"" bulleted list item, level 2 Fever
"" bulleted list item, level 2 Abrupt onset of generalized or locallized severe pain, often in an arm or leg
  bulleted list item, level 2 Dizziness
"" bulleted list item, level 2 Influenza-like syndrome
  bulleted list item, level 2 Confusion
  bulleted list item, level 2 A flat red rash over large areas of the body (only occurs in 10% of cases)

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How is invasive group A streptococcal disease treated?

GAS infections can be treated with many different antibiotics. For STSS and necrotizing fasciitis, high dose penicillin and clindamycin are recommended. For those with very severe illness, supportive care in an intensive care unit may also be needed. For persons with necrotizing fasciitis, early and aggressive surgery is often needed to remove damaged tissue and stop disease spread. Early treatment may reduce the risk of death from invasive group A streptococcal disease. However, even the best medical care does not prevent death in every case.

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What can be done to help prevent group A streptococcal infections?

The spread of all types of GAS infection can be reduced by good hand washing, especially after coughing and sneezing and before preparing foods or eating. Persons with sore throats should be seen by a doctor who can perform tests to find out whether the illness is strep throat. If the test result shows strep throat, the person should stay home from work, school, or day care until 24 hours after taking an antibiotic. All wounds should be kept clean and watched for possible signs of infection such as redness, swelling, drainage, and pain at the wound site. A person with signs of an infected wound, especially if fever occurs, should immediately seek medical care. It is not necessary for all persons exposed to someone with an invasive group A strep infection (i.e. necrotizing fasciitis or strep toxic shock syndrome) to receive antibiotic therapy to prevent infection. However, in certain circumstances, antibiotic therapy may be appropriate. That decision should be made after consulting with your doctor.

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Date: April 3, 2008
Content source: National Center for Immunization and Respiratory Diseases: Division of Bacterial Diseases
 
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