Health Library

What Is a Group A Strep Infection?

Group A strep (GAS) is short for group A streptococcus, a type of bacteria. These

bacteria
usually live harmlessly on the skin and in the nose and throat. Sometimes they cause mild skin or throat infections that are easily treated with antibiotics. Less often, they can cause more serious infections or problems in other parts of the body.

What Problems Can Group A Strep Cause?

GAS infections can show up in lots of different ways. Conditions often caused by GAS include:

• throat infections, such as strep throat or tonsillitis
• skin and soft tissue infections, such as impetigo or cellulitis
• scarlet fever

Less common but more serious problems include:

• deeper infections in the throat, such as peritonsillar abscess or retropharyngeal abscess
• other infections, such as pneumonia, sepsis, sinusitis, vaginitis, osteomyelitis, meningitis, bacteremia (infection in the bloodstream), and arthritis (infection in a joint)
• rheumatic fever, which can follow a throat infection and lead to inflammation and damage in organs like the heart, joints, or brain. It’s very rare in North America and Europe.
• a kidney problem called post-streptococcal glomerulonephritis
• PANDAS/PANS
• toxic shock syndrome
• necrotizing fasciitis, a severe, deep infection in the skin, muscle, and fat

An invasive GAS infection is one that happens when GAS infects a part of the body where the bacteria don’t usually live.

How Do Group A Strep Infections Spread?

GAS bacteria can spread through:

• saliva (spit) or mucus from the nose and throat, which can be released into the air when someone coughs and sneezes
• contact with infected skin

People who carry the bacteria in their body but have no symptoms can still spread the bacteria but are much less contagious. GAS can get into the body through breaks in the skin, such as a cut, insect bite, or burn. Sometimes, invasive GAS infections happen after a viral infection, like the flu. People with weak immune systems are more likely to develop a serious GAS infection.

How Are Group A Strep Infections Treated?

Doctors usually treat GAS infections with antibiotics. Depending on where the infection is, they might use other treatments.

A person with a mild GAS infection usually stops being contagious 24 hours after starting treatment with an antibiotic. They should take all the antibiotics as prescribed to prevent the other health problems that GAS can cause.

Often, people with an invasive GAS infection need to be treated in a hospital.

Can Group A Strep Infections Be Prevented?

To help prevent GAS infections, adults and kids should:

• Wash their hands well and often.
• Cover their nose and mouth with a tissue when coughing or sneezing. If a tissue isn’t handy, they should cough or sneeze into their upper arm or elbow, not their hands. 
• Stay home from work or school when sick.
• Use their own toothbrushes, cups, or eating utensils and not share these items.
• Treat and cover areas of skin infections.

What Else Should I Know?

Invasive GAS infections are rare. Sometimes, news reports note that hospitals are treating more children with invasive GAS infections than usual. But these infections aren’t new and are very treatable.

If you think that your child might have symptoms of a GAS infection, call your doctor. When treatment is needed, the earlier it starts, the better.

To help protect your family from viral illnesses that can sometimes lead to GAS infections, make sure everyone is up to date on their flu, chickenpox, and COVID-19 vaccines.