Invasive group A streptococcus factsheet

Introduction

Group A streptococcus (Strep A) is a type of bacteria found on the skin and in the throat. It usually causes common childhood illnesses like:

In some cases, Strep A can lead to more severe illness, like:

  • rheumatic fever - an autoimmune condition that can affect the heart, joints, brain and skin
  • glomerulonephritis - inflammation of the tiny filters in the kidneys
  • invasive group A streptococcal disease (iGAS) – a rare, life-threatening infection.

Invasive group A streptococcal disease (iGAS)

Invasive group A streptococcal disease (iGAS) happens when the bacteria enter parts of the body where they are not normally found, like the:

  • muscle
  • lungs
  • bloodstream.

iGAS is a medical emergency and needs urgent treatment in hospital. It can lead to life-threatening infections, including:

  • sepsis – where the body's response to an infection damages its tissues and organs
  • toxic shock syndrome – where bacteria release harmful toxins into the bloodstream
  • necrotising fasciitis – when bacterial infection quickly destroys soft tissue and connective tissue around the muscles, nerves and fat
  • meningitis – when bacteria cause inflammation of the membranes that protect the brain and spinal cord
  • pneumonia – when bacteria cause inflammation and fluid buildup in the air sacs of the lungs. 

 Signs and symptoms

Strep A Infection

Symptoms of a strep A infection depend on where the infection is and how severe it is.

General symptoms can include:

  • fever
  • muscle pain
  • sores
  • redness and swelling.

Symptoms may appear:

  • in the throat – like strep throat or tonsillitis
  • on the skin – like impetigo or cellulitis
  • in both places – like scarlet fever.

iGAS Infection

iGAS symptoms appear 12–24 hours after infection and include:

  • high fever, chills or sweating
  • shortness of breath
  • chest pain
  • severe muscle pain
  • nausea or vomiting
  • redness around wounds or sores.

Go to the nearest emergency department immediately if your child shows signs of iGAS.

Diagnosis

Your child’s doctor will check their symptoms and may do a blood test or swab from the throat or skin.

Treatment

Strep A and iGAS are treated with antibiotics to kill the bacteria. 

Your child must stay home until at least 24 hours after starting antibiotics. Keep your child at home for the full course of antibiotics to help stop the spread.

Severe infections and iGAS are treated in hospital. 

Other family members may also be given antibiotics if they have been exposed.

 Management

Preventing the spread of invasive group A streptococcus

Step A bacteria is very common. Around 1 in 3 people carry the bacteria without being sick.

Strep A spreads through:

  • air droplets from coughing, sneezing or talking
  • touching skin with the bacteria
  • touching contaminated objects, like toys or water bottles.

To help prevent the spread, teach your child to:

  • cough or sneeze into their elbow, tissue, or hand
  • wash hands regularly with soap
  • wear a mask if unwell
  • avoid sharing water bottles, cutlery or personal items.

You can also help your child by:

  • keeping cuts and wounds clean and covered
  • seeing a doctor early if your child has a sore throat or skin sores
  • seeing a doctor if your child is sick and has had contact with someone with Strep A in the last 30 days
  • keeping up to date with flu and chickenpox vaccinations.

Risk factors for invasive group A streptococcus

Children are more at risk of getting Strep A because they:

  • are still learning good hygiene habits
  • have close contact with others during play
  • spend time in group settings like school or daycare.

Children can be at a higher risk if they:

  • are under 1 year old
  • are a newborn baby and have a parent with iGAS
  • have had a recent injury, burn or surgery
  • have had recent influenza or chickenpox infections
  • have a weak immune system
  • are undergoing treatment like chemotherapy or using steroids that can weaken the immune system
  • are Aboriginal and/or Torres Strait Islander
  • are living with someone who has iGAS.

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Disclaimer

This factsheet is provided for general information only. It does not constitute health advice and should not be used to diagnose or treat any health condition.

Please consult with your doctor or other health professional to make sure this information is right for you and/or your child.

The Sydney Children’s Hospitals Network does not accept responsibility for inaccuracies or omissions, the interpretation of the information, or for success or appropriateness of any treatment described in the factsheet.

© Sydney Children’s Hospitals Network 2025


This factsheet was produced with support from John Hunter Children's Hospital.