Group A streptococcal infection
Key facts
- Group A streptococcus (GAS) is a type of bacteria often found in the throat and on the skin.
- It can cause strep throat, scarlet fever, impetigo, cellulitis and other rare but severe health conditions.
- The best way to prevent group A streptococcal infections is to follow good hygiene practices and stay home when you're sick.
- GAS infections can be treated with antibiotics.
What is group A streptococcus?
Group A streptococcus (GAS) is a type of bacteria. It is also called:
- group A strep
- strep A
- type A streptococcal
- streptococcus pyogenes
GAS is often found in the throat and on the skin of people who do not have any symptoms.
Healthy people can be carriers of GAS without having any symptoms or becoming unwell.
What is group A streptococcal infection?
GAS can cause infections in some people, making them unwell. Group A streptococcal infections can cause:
- sore throat, also known as strep throat
- tonsillitis
- scarlet fever
- skin infections, such as impetigo and cellulitis
Invasive group A streptococcal (iGAS) infections
In rare cases the bacteria can cause a severe, life-threatening infection known as invasive group A streptococcal (iGAS) infection. Types of iGAS are:
- bone and joint infections
- blood infection
- pneumonia
- meningitis
- sepsis
- necrotising fasciitis (sometimes called 'flesh-eating bacteria' — a life-threatening soft tissue infection)
- toxic shock syndrome
People with iGAS infections need to be treated in hospital.
What are the symptoms of group A streptococcal infection?
The symptoms of group A streptococcal infection depend on where the infection is in your body. One common symptom of GAS infection is fever.
Early symptoms of iGAS infections can also include fever and:
- nausea and vomiting
- shortness of breath
- headache
- severe muscle aches
- redness at the site of a skin wound
- skin rash
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What causes group A streptococcal infection?
If you are in close contact with someone with group A streptococcal bacteria, you may become infected if you:
- breathe in droplets from their coughs or sneezes
- touch something with droplets on it and then touch your mouth or nose
- touch them or have contact with infected skin sores
- kiss them
Anyone can get a group A streptococcal infection, but people who are most at risk are:
- children under 5 years of age, especially newborn babies
- people who are pregnant or have recently given birth
- older people
- people who live with someone who has a GAS infection
- people with poor access to hygiene facilities
- people who live or spend time in crowded conditions
- people with weak immune systems or chronic illnesses (such as diabetes or heart disease)
Children are more likely to become infected because they tend to be less aware of hygiene than adults. They also generally spend more time in crowded environments, such as schools, and play in close physical contact.
When should I see my doctor?
Visit your doctor if you have a severe sore throat, skin sores or a wound that is not getting better.
If you think you or someone you care for has a group A streptococcal infection, it is important to see a doctor as soon as possible.
The infection can spread through the body and can become serious if not promptly treated with antibiotics.
A person with iGAS can become very sick within 12 to 24 hours, so it's important to seek medical care promptly.
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How is group A streptococcal infection diagnosed?
Your doctor will ask about your symptoms and do a physical examination.
Depending on your symptoms and the type of infection you have, your doctor will recommend tests to check if you have a group A streptococcal infection. These may include:
- a swab of your throat or a skin sore
- blood tests
- a sample of other body fluid
- x-rays or other imaging tests
How is a group A streptococcal infection treated?
Group A streptococcal infections are treated with antibiotics.
Your doctor will work out which antibiotic is best, depending on where your infection is located and how serious it is.
People with invasive group A streptococcal (iGAS) infection need to be treated in hospital.
Can group A streptococcal infection be prevented?
You can help prevent group A streptococcal infections by maintaining good hygiene. To decrease the spread of bacteria, wash your hands often, especially after sneezing or coughing and before preparing, serving or eating food.
Ensure surfaces (such as bathroom sinks, taps and door handles) as well as clothes and bedlinen are kept clean to protect all the members of your household.
If you or your child have strep throat or another form of GAS infection, you should stay home from pre-school, school or work for at least 24 hours after starting antibiotic treatment.
Antibiotics for close contacts of people with iGAS infection
Talk to your doctor if you have been in close contact with someone with an invasive group A streptococcal infection.
Your doctor may recommend you take a course of antibiotics to reduce your risk of infection.
Complications of group A streptococcal disease
In some people, a group A streptococcal infection can lead to serious complications. These can include:
- Rheumatic fever, which can affect your heart, joints, brain and skin.
- Post-streptococcal glomerulonephritis (which affects your kidneys).
- Severe scarring or limb loss from necrotising fasciitis or toxic shock syndrome.
Resources and support
If you are concerned about GAS infection you can call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.
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Last reviewed: November 2023
