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Additional Information
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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. 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.
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:
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No illness |
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Mild illness (strep throat or a skin infection such as impetigo) |
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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.
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.
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 is the rate of serious group B strep infections among non-pregnant adults?
The rates of serious group B strep infections are much higher among newborns than among any other age group. Nonetheless, serious group B strep infections occur in other age groups in both men and women. Among non-pregnant adults, rates of serious disease range from 4.1 to 7.2 cases per 100,000 population.
How serious is this infection in adults?
The average death rate for invasive infections (infections where the bacteria have entered a part of the body that is normally not exposed to bacteria) is 8-10% for adults ages 18-64 and 15-25% for adults 65 years of age and over. Mortality rates are lower among younger adults, and adults who do not have other medical conditions.
Who is more at risk for adult group B strep disease?
The rate of serious group B strep disease increases with age. The average age of cases in non-pregnant adults is about 60 years old. Most adult group B strep disease occurs in adults who have serious medical conditions. These include: diabetes mellitus; liver disease; history of stroke; history of cancer; or bed sores.
Among the elderly, rates of serious group B strep disease are more common among residents of nursing facilities, and among bedridden hospitalized patients. Group B strep disease among non-pregnant adults may often be acquired after recent trauma, or after having certain invasive hospital procedures like surgery.
What are the symptoms of group B strep disease in adults?
Sometimes group B strep can cause mild disease in adults, such as urinary tract infections (UTIs, also called bladder infections). These are treated the same way urinary tract infections caused by other bacteria are treated, with antibiotics, and are usually not that serious.
Serious, invasive disease (infections where the bacteria have entered a part of the body that is normally not exposed to bacteria) can present in a number of different ways. The most common problems in adults are: bloodstream infections, pneumonia, skin and soft-tissue infections, and bone and joint infections. Rarely in adults, group B strep can cause meningitis (infection of the fluid and lining surrounding the brain).
How are serious group B strep infections diagnosed?
If doctors suspect a patient has an invasive group B strep infection, they will take a sample of sterile body fluids, such as blood or spinal fluid. Group B strep disease is diagnosed when the bacteria are grown from cultures of those fluids. Cultures take a few days to grow.
How are serious group B strep infections treated?
Group B strep bacteria are usually treated with penicillin or other common antibiotics. Sometimes soft tissue and bone infections may need surgery. Your treatment will vary according to the kind of infection with group B strep you have, and you should ask your doctors about specific treatment options.
Is there any way to prevent group B strep disease in adults?
Standard infection control measures, particularly for patients who are hospitalized or in nursing homes, help reduce the risk of bacterial infections, including those caused by group B strep. Researchers are currently working on developing a group B strep vaccine which may one day be available to the public as a way to prevent serious group B strep infections among adults, particularly among the elderly.
Find out more about the different strep infections from the CDC at: http://www.cdc.gov/strep/
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