Group A streptococcal (strep) infections are caused by group A Streptococcus, a type of bacteria responsible for a variety of health problems.

These infections can range from relatively mild illnesses such as strep throat, scarlet fever, and impetigo (a skin infection) to life-threatening conditions such as toxic shock syndrome and necrotizing fasciitis (“flesh-eating” infection). Most people are familiar with strep throat, which along with impetigo is the most common form of the disease.

Health experts estimate that more than 10 million mild throat and skin infections like these occur every year. Serious, sometimes life-threatening, illness may occur when bacteria get into parts of the body where bacteria usually are not found, such as the blood, muscles, or the lungs. These infections are termed "invasive group A strep disease."


Strep throat is a common type of sore throat in children, but it’s not very common in adults. If you have strep throat infection, you will have a red and painful sore throat and may have white patches on your tonsils. You may also have swollen lymph nodes in your neck, run a fever, and have a headache. Nausea, vomiting, and abdominal pain can occur but are more common in children than in adults. Your health care provider may call it acute streptococcal pharyngitis. Strep throat may sometimes lead to scarlet fever.

Untreated group A strep infection can result in rheumatic fever and poststreptococcal glomerulonephritis (PSGN). Rheumatic fever develops about 18 days after a bout of strep throat and causes joint pain and heart disease. It can be followed months later by Sydenham's chorea, a disorder in which the muscles of the torso and arms and legs are marked with dancing and jerky movements. PSGN is an inflammation of the kidneys that may follow an untreated strep throat but more often comes after a strep skin infection. Both disorders are rarely seen in the United States because of prompt and effective treatment of most cases of strep throat.


You can get strep throat and other group A strep infections by direct contact with saliva or nasal discharge from an infected person. Most people do not get group A strep infections from casual contact with others, but a crowded environment like a dormitory, school, or an institutional setting such as a nursing home can make it easier for the bacteria to spread. There have also been reports of contaminated food, especially milk and milk products, causing infection.

To prevent streptococcal infections, care should be taken to observe the following:

  • Practice good handwashing and adequate hygiene to combat hand carriage and transmission.

  • Always take the full course of any antibiotic, exactly as prescribed.

  • Varicella (chickenpox) infection is the most commonly identified risk factor for strep toxic shock syndrome and necrotizing fasciitis in children. Keep the fingernails of children with varicella well-trimmed, their hands well washed, and take efforts to discourage scratching of lesions. Provide varicella vaccine to prevent varicella infection.

  • Group A Streptococcus bacteria are spread more easily in areas of crowding. Separate children with strep throat or skin infections. Children with streptococcal infections should not return to school or a childcare facility until after receipt of at least 24 hours of effective antibiotic treatment.

  • Exclude persons with group A strep infection or ANY exposed skin lesions from food handling until after receipt of at least 24 hours of appropriate antibiotic treatment).

  • Exclude persons with group A strep infection/pharyngitis from patient care activities until after receipt of at least 24 hours of appropriate antibiotic treatment.


Health care professionals can test for strep by swabbing the throat to quickly see if group A strep bacteria are present. A strep test is needed to tell if you have strep throat; just looking at your throat is not enough to make a diagnosis. If the test is positive, your health care provider can prescribe antibiotics. If the strep test is negative, but your clinician still strongly suspects you have this infection, then your clinician may perform a throat culture swab to test for the bacteria, but those results will take longer to come back. The results of these throat cultures will affect what your health care provider decides to be the best treatment. Most sore throats are caused by viral infections, however, and antibiotics are useless against them.

If you have a strep infection, your health care provider will prescribe an antibiotic. This will help reduce symptoms, and after 24 hours of taking the medicine, you will no longer be able to spread the infection to others. Treatment will also reduce the chance of complications. Health experts think penicillin is the best medicine for treating strep throat because it has been proven to be effective, safe, and inexpensive. If you are allergic to penicillin there are other antibiotics your health care provider can give you to clear up the illness. Children with strep throat are usually treated with amoxicillin. During treatment, you may start to feel better within four days. This can happen even without treatment. Still, it is very important to finish all your medicine to prevent complications.

More Resources
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More Information on Group A Strep (CDC)
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Types of Group A Strep Infections (CDC)
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