Group A Streptococcal Infections - Severe Group A Streptococcal Infections - Severe
Group A streptococcal infections are caused by group A streptococcus, a bacterium responsible for a variety of health problems. These infections can range from mild skin infection or sore throat to invasive, life-threatening conditions such as toxic shock syndrome and necrotizing fasciitis. Most people are familiar with strep throat, which along with minor skin infection, is the most common form of the disease. Experts estimate that more than 10 million mild infections like these occur every year.
In addition to strep throat and superficial skin infections, group A strep bacteria can cause infections in tissues at specific body sites, including lungs, bones, spinal cord, and the abdominal cavity.
What are the more severe streptococcal infections?
Some types of group A streptococcus bacteria cause severe infections. These include:
- Bacteremia (blood stream infections)
- Toxic shock syndrome
- Necrotizing fasciitis (sometimes called flesh-eating disease)
According to the U.S. Centers for Disease Control and Prevention (CDC), 8,800 cases of severe group A streptococcal disease were reported in 2000, a rate of 3.1 per 100,000 people.
All severe group A strep infections may lead to shock, organ failure, and death. Health care workers must recognize and treat such infections quickly.
Doctors diagnose these infections by looking at blood counts and doing urine tests as well as cultures of blood or fluid from a wound site. Antibiotics include penicillin, erythromycin, and clindamycin. If tissue damage is severe, a doctor may need to remove the tissue surgically or amputate the limb.
Who is at greatest risk for severe infection?
- Children with chickenpox
- People with suppressed immune systems
- Burn victims
- Elderly people with cellulitis, diabetes, blood vessel disease, or cancer
- People taking steroid treatments or chemotherapy
- Intravenous drug users
Severe group A strep disease may also occur in healthy persons with no known risk factors.
Research
Through research, scientists have learned that there are more than 120 different strains of group A streptococci, each producing its own unique proteins. Some of these proteins are responsible for specific group A streptococcal diseases. With support from the National Institute of Allergy and Infectious Diseases (NIAID), scientists have determined the genetic sequence, or DNA code, for three different strains of the group A streptococcus organism.
By studying an organism's genes, scientists learn which proteins are responsible for virulence, crucial information that will lead to new and improved drugs and vaccines. NIAID funds are supporting research for developing a group A streptococcus vaccine. An effective vaccine will prevent not only strep throat and impetigo, but more serious invasive disease and post-infectious complications like rheumatic fever.
Two different vaccine approaches are being evaluated in clinical trials in the NIAID Vaccine and Treatment Evaluation Units. More information is available at the following NIAID Web site: http://www.niaid.nih.gov/dmid/vaccines/.
Source: National Institute of Allergy and Infectious Diseases
August 2000.
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