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Group B streptococcal disease

8-minute read

If your baby has difficulty breathing, a high fever, is vomiting or has floppy arms or legs, this is an emergency. Call triple zero (000) and ask for an ambulance.

Key facts

  • Group B streptococcus (GBS) is a type of bacteria that many healthy adults have in their bodies but without their becoming unwell.
  • Newborns, pregnant women, older adults and people with a weakened immune system may become very unwell if infected with GBS.
  • Pregnant women are checked for GBS since the infection can be passed on to the baby during a vaginal childbirth.
  • Pregnant women who test positive for GBS are treated with antibiotics in hospital shortly before their baby is born.
  • Babies who are born to mothers with GBS need to be monitored closely for signs of GBS infection.

What is group B streptococcal infection?

Group B streptococcus (GBS or ‘group B strep’) is a type of bacteria commonly found in the gastrointestinal system, or gut, and the urogenital system, including the urethra and vagina. Healthy adults of any age can be carriers of GBS without having any symptoms or becoming unwell. For children — and in particular, newborn babies — GBS can be very dangerous and so needs urgent medical attention.

Older adults and people with ongoing medical conditions, such as diabetes and cancer, are also at increased risk of GBS infection

What are the symptoms of group B Streptococcal infection?

GBS infections in adults can cause a wide range of symptoms since they can affect many different parts of the body. GBS can cause skin and soft tissue infections, blood infections, urinary tract infectionspneumoniabone and joint infections, and meningitis.

A common symptom of GBS infection is fever, but other symptoms will depend on the type of GBS infection — for example, shortness of breath or cough in cases of pneumonia, or pain when passing urine if a urinary tract infection is involved.

GBS infection can cause a baby to become unwell shortly after they are born. Symptoms of GBS infections in newborn babies include:

  • difficulty breathing, breathing too quickly or noisy breathing
  • being very sleepy and not interested in breastfeeding or drinking from a bottle
  • vomiting
  • being too hot or too cold
  • pale or mottled skin
  • floppy arms and legs

If your baby develops signs of GBS, they need urgent medical attention. GBS infection can happen within 24 hours of a baby being born and is called ‘early onset GBS’. In some babies, GBS infection develops later, a week or more after birth. This is known as ‘late onset GBS’.

When should I see my doctor?

If you are concerned your baby may have a GBS infection, or they have any of the symptoms of GBS infection described above, you should let a doctor know immediately.

If your baby has difficulty breathing, a high fever, is vomiting or has floppy arms or legs, this is an emergency. Call triple zero (000) and ask for an ambulance.

If you are pregnant, a GBS infection can cause both you and your unborn baby to become very unwell. It can lead to a urinary tract infection (UTI) and cause an infection in the fluid that surrounds your baby, known as the amniotic fluid. If you are pregnant and think you may have a GBS infection, or have a fever or pain in your abdomen, contact your doctor as soon as possible.

If you have had a GBS test return a positive result while pregnant, speak to your doctor about developing a labour and delivery plan to reduce your baby’s risk of becoming infected.

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What causes group B streptococcal infection?

GBS infections are caused by the GBS bacteria and generally occur when babies, pregnant women, older adults or people with health conditions associated with weakened immune systems become infected.

GBS is commonly found in healthy people. They are not considered to be infected with GBS but rather, they are carriers of the bacteria. They do not require treatment.

Women who are carriers of GBS can pass the bacteria on to their baby during a vaginal birth.

You cannot become infected with GBS through contaminated food or water, having sex with someone with GBS, or through poor hygiene.

How is group B streptococcal infection diagnosed?

GBS infection can be diagnosed from blood, urine or spinal fluid samples. The symptoms you have will influence which tests your doctor may ask for.

GBS can cause serious infections in newborn babies, and it is recommended that pregnant women are tested for GBS around the 36th week of pregnancy since carriers of the bacteria don’t generally know they are a carrier until they are tested.

If you are likely to give birth early, your doctor may recommend you have a GBS test earlier on in your pregnancy.

A vaginal swab — and sometimes an anal swab — is used to obtain a sample which a lab then examines for GBS bacteria. You can do this test yourself at home or at the doctor’s clinic, or you can ask your doctor or nurse to do the swab for you if you prefer.

If you test positive while pregnant, your baby will need to be monitored in hospital for signs of GBS infection. This includes regular checks of the baby’s breathing, heart rate and temperature for at least 24 hours after they are born. If they show signs of GBS infection, your doctor will recommend a blood test and maybe other tests too, depending on the baby’s symptoms. These other tests could include a chest x-ray or a lumbar puncture of the baby’s spine.

How is group B streptococcal infection treated?

GBS infections both in adults and babies can be treated with antibiotics. If your baby is diagnosed with an infection, they will be given intravenous antibiotics urgently. They will normally need the antibiotics for at least 1 week, and for as long as they continue to have symptoms.

Your baby will have blood tests during this time to check the levels of antibiotics in their blood and to see if the infection is going away. Not using antibiotics to treat the infection in a baby can be very dangerous.

Can group B streptococcal infection be prevented?

GBS infection cannot be prevented entirely, but you can reduce the risk of passing an infection to your baby during birth by receiving antibiotics shortly before. Pregnant women should be tested for GBS before they go into labour so they can receive the antibiotics in hospital.

The antibiotics are delivered from an intravenous drip through a vein in your arm or hand. This way, the medicine travels through your body to your baby before they are born, helping to prevent infection in the first few days of life. The antibiotics should be given at least 4 hours before your baby is born.

If your baby is born by caesarean section (C-section), whether planned or unplanned, you do not need antibiotics for GBS. You may be offered other antibiotics as part of the routine care after surgery.

What can complicate a group B streptococcal infection?

Pregnant women who have become unwell from a GBS infection are more likely to go into labour before their baby’s due date, and although rare, their baby is more likely to be stillborn. If you are pregnant and found to have a GBS infection, you will be treated with antibiotics to protect you and your baby.

Babies are more likely to become infected with GBS if they are born before 37 weeks of pregnancy, if their mother has a high temperature (fever) during labour or on the day after, or had a prior pregnancy or baby infected with GBS.

In cases of a severe infection, GBS can cause a blood infection (sepsis) or an infection of the membranes surrounding the brain and spinal fluid (meningitis).

Resources and support

  • If you are worried that your pregnancy or baby may be affected by GBS, call Pregnancy, Birth and Baby on 1800 882 436 to speak to a maternal child health nurse, or talk to your midwife or doctor.
  • Read more information about GBS in the RANZCOG factsheet.
  • Information in other languages — Do you prefer to read languages other than English? NSW Health has fact sheets on pregnancy screening for Group B streptococcus in 18 different languages.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: August 2021

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