Group A Streptococcus

Group A streptococcus, or group A strep, is a bacterium commonly found in the throat and on the skin. Group A strep bacteria can cause a range of infections, from relatively mild sore throats and skin infections to life-threatening invasive disease.
Group A strep bacteria are spread by direct person-to-person contact.
Group A strep infections can usually be treated with antibiotics.
Two types of very serious group A strep infections are necrotizing fasciitis and streptococcal toxic shock syndrome.
To prevent group A strep infections: 1) wash hands thoroughly and often, 2) get a throat culture for a sore throat with fever, and 3) keep wounds clean and seek medical care for infected wounds with fever.

What is group A streptococcus (group A strep)?

Group A streptococcus (group A strep) is a bacterium that is commonly found in the throat and on the skin. The letter "A" refers to a classification of bacteria in the genus Streptococcus according to the makeup of the organism's cell wall. Group A strep bacteria might cause no symptoms of disease, but they can also cause infections that range from mild to life-threatening.

Where is group A strep found?

Group A strep bacteria are found worldwide.

How do people get group A strep infections?

Group A strep bacteria are spread by direct person-to-person contact. The bacteria are carried in discharges from the nose or throat of an infected person and in infected wounds or sores on the skin. The bacteria are usually spread when infected secretions come in contact with the mouth, nose, or eyes of an uninfected person. They can also enter the body through a cut or scrape.

The risk of spreading the infection is highest when an infected person is ill or has an infected wound. Infected persons who have no symptoms are much less contagious. Household objects like plates, cups, and toys do not play a major role in the spread of group A strep.

What kinds of illnesses does group A strep cause?

Group A strep usually causes relatively mild illnesses, such as streptococcal sore throat (strep throat) and streptococcal skin infections (impetigo). Group A strep can also cause more serious illnesses such as scarlet fever, rheumatic fever, postpartum fever, wound infections, and pneumonia.

Occasionally, a deadly type of group A strep bacteria can invade the blood, muscle and fat tissue, or lungs and cause a serious and often life-threatening type of infection called invasive group A strep. Two rare, but very severe, forms of invasive group A strep infections are necrotizing fasciitis and streptococcal toxic shock syndrome.

Necrotizing fasciitis (sometimes referred to as "the flesh-eating disease") is an infection that attacks the deep layers of tissue (fascia). It is usually caused when a deadly strain of group A strep infects an opening in the skin. For unknown reasons, the strain becomes very aggressive and releases a toxin (poison) that quickly and irreparably destroys flesh and muscle. Doctors often must remove skin, large groups of muscle, or entire limbs to save a person's life.

Streptococcal toxic shock syndrome, another type of rapidly progressing strep infection, causes a dangerous drop in blood pressure, shock, and damage to the kidneys, liver, and lungs. As in necrotizing fasciitis, the toxin damages the tissues and organs so quickly that treatment is difficult and often too late.

What are the signs and symptoms of group A strep infection?

Signs and symptoms depend on the type of illness caused by group A strep. Strep throat causes fever, sore throat, and swollen lymph glands. Strep skin infection causes red, weeping skin sores. Scarlet fever causes all the symptoms of strep throat plus a characteristic rash on the neck, chest, skin folds, and inner thighs. The rash can often be felt easier than seen.

Early signs and symptoms of necrotizing fasciitis are fever and severe pain, swelling, heat, and redness at a wound site. Necrotizing fasciitis is known for the speed with which it attacks and destroys muscle and flesh.

Early signs and symptoms of streptococcal toxic shock syndrome often include fever, dizziness, and confusion. Streptococcal toxic shock syndrome has no sign or symptom that distinguishes it from other illnesses.

How soon after exposure do symptoms appear?

Symptoms appear quickly, usually within 1 to 3 days.

How is group A strep infection diagnosed?

The infection is diagnosed by culture of the organism in a laboratory. Strep throat can also be diagnosed by a rapid strep test.

Who is at risk for group A strep infections?

Anyone can become infected with group A strep. However, people with long-term illnesses like cancer, diabetes, and kidney disease, and those who use medications such as steroids, are at higher risk for invasive disease. Breaks in the skin, like cuts, surgical wounds, or chickenpox blisters, can also provide an opportunity for the bacteria to enter the body.

What is the treatment for group A strep infection?

Group A strep infections can be treated with many different antibiotics. Early treatment can reduce the risk of death from invasive disease, but it does not prevent death in every case.

How common is group A strep infection?

Mild group A strep disease is very common in the United States; several million people get strep throat and minor strep skin infections each year. Approximately 10,000 people develop invasive group A strep disease each year, resulting in more than 2,000 deaths. Of these, 500 to 1,500 are cases of necrotizing fasciitis and a similar number are cases of streptococcal toxic shock syndrome. Group A strep is fatal to about 20% of patients with necrotizing fasciitis and 60% of patients with streptococcal toxic shock syndrome.

Is group A strep infection an emerging infectious disease?

Yes. Health problems associated with strep A bacteria are not new, but reports of fatal infection with invasive strep A bacteria have been increasingly recognized in the United States since 1987. Researchers do not know why the new strain of strep A is on the increase or why it targets certain otherwise healthy people.

How can group A strep infections be prevented?

Wash hands thoroughly and often with soap and warm water, especially after coughing and sneezing, before preparing foods, and before eating.
Anyone with a sore throat with fever should see a health-care provider to get a throat culture or rapid test to detect strep infection. Persons with strep throat should stay home from work, school, or day care until 24 hours after taking an antibiotic.
Keep all wounds clean, and watch for possible signs of infection: rapidly increasing redness, swelling, drainage, and pain at the wound site. Anyone with signs of an infected wound, especially if fever develops, should seek medical care right away.

This fact sheet is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health-care provider. If you have questions about the disease described above, consult a health-care provider.