Understanding Group B Streptococcal (GBS) Infection

Understanding group B Streptococcal (GBS) infection

What is Group B Streptococcus (GBS)?
Group B streptococcus (GBS) is a very common bacterium. It occurs naturally in many people. It typically causes no harm or symptoms. Up to one in three people carry GBS in the gut (bowel) and in women it may be found in the vagina (birth canal). It is usually intermittent in nature i.e. it can come and go. GBS is not sexually transmitted, nor is it a sign of ill health or poor hygiene.

What is GBS infection?
Although GBS carriage in an adult is not serious, it can lead to GBS infection in babies before, during or shortly after birth. This infection may cause serious complications and can even be life-threatening. Many babies are exposed to GBS, but only those susceptible to the bacterium will become infected. It is not known why some babies are susceptible and others are not.

How can GBS infection be prevented?
Screening all women in pregnancy to find GBS is not routinely offered. University Hospital Galway (UHG) follows the guidelines of the Royal College of Obstetricians and Gynaecologists (UK) who recommend a risk factor approach for preventing GBS infection in the newborn.

This approach may prevent GBS infection in the newborn by identifying those women at risk (see below for risk factors) and treating them by giving antibiotics intravenously (through a vein) from the beginning of labour until their baby is born.

It is not recommended to undergo a caesarean section to prevent GBS infection in babies. Caesarean sections have not been shown to eliminate the risk of GBS infection in babies, and a caesarean section may pose other risks for mothers and babies. Hand-washing and proper hand-drying before handling the baby can lower the risk as GBS can be carried on the skin.

How do I know if I am carrying GBS?
Vaginal GBS colonisation has no symptoms and can be intermittent (i.e. may come and go). It is possible to screen. If a test is done, the most sensitive method of detection requires swabs from the vagina and rectum that are cultured in the laboratory.

However routine screening for the detection of GBS in pregnancy is not carried out in University Hospital Galway (UHG). Currently the evidence suggests that screening all pregnant women routinely may not be beneficial overall.

GBS may also be detected on a laboratory sample of urine. Antibiotics will be given at the time of detection if GBS is found in a sample of urine. Carrying GBS in pregnancy does not automatically mean that a baby will develop GBS infection.

There are some situations where a woman will be offered antibiotics in labour to help prevent GBS infection in her baby and these may include:

1. Mothers who have had a previous baby with a GBS infection.
2. Mothers who have been found to carry GBS on vaginal swab or in their urine during this pregnancy or previous pregnancy.
3. Where a women has a raised temperature in labour of 38°C or higher.
4. If your baby is born Preterm before 37 completed weeks of pregnancy.

If you have any of these risk factors, as soon as you go into labour or your waters break you should present to hospital immediately, as it is important that you have antibiotics as soon as possible.

What is the treatment?
The use of intravenous antibiotics in labour has been shown to be effective in the prevention of newborn GBS infections. These antibiotics (normally penicillin) are offered every four hours from the start of labour until the baby is born, in women who have any of the above mentioned risk factors. At least 4 hours of antibiotic cover before the birth is desirable.

Are there any risks with antibiotics?
There are risks associated with the use of any drug. Some women have a specific allergy to antibiotics. This may include death or injury to a very few women from an allergic reaction (anaphylaxis). Some women may experience temporary side effects such as diarrhoea or nausea. However for most women antibiotics are safe.

It is therefore sensible to discuss antibiotic options with your healthcare provider to ensure the most appropriate care for you and your baby.

NB—It is essential to inform your health professionals if you are allergic to penicillin.

Who does not require treatment?
• It is not necessary to have antibiotics if you are undergoing a planned Caesarean section, unless the membranes are not intact (waters break) or you start labour before delivery.

• If GBS is found incidentally on a vaginal swab during a current pregnancy, treating with antibiotics at the time is not effective at preventing GBS infection in the newborn. However antibiotics are recommended during labour.


Babies born to mothers who have had at least 4 hours of antibiotic cover before delivery should be:

• If completely healthy, no antibiotics are required for the baby; however the baby should remain in hospital for at least 24 hours.

Babies born to mothers who have not had at least 4 hours of antibiotics before delivery should:
• Be monitored for 12 hours.
• Stay in hospital for 24 hours.

How to recognise GBS infection in babies?
Early onset GBS (EOGBS) presents soon after the birth. Most babies show signs of EOGBS infection within 12-24 hours of birth. It is the most common type of GBS infection accounting for 80% of GBS cases in babies. Late onset GBS is much less common and can affect your baby until they are 3 months old.

Possible signs of GBS infection include:
• Grunting (noisy breathing) or fast breathing.
• Abnormal drowsiness / sleepiness.
• Poor feeding, vomiting.
• Poor handling, irritability, high-pitched cry.
• Tense, bulging fontanelle.
• Unusual changes in behaviour; stiffness, unusually floppy, seizures.
• Pale, blotchy skin or rash.
• High or low temperature, skin feels too hot or cold.

Remember to trust your instincts. If you are concerned that your baby is showing any signs consistent with GBS infection call your midwife (while in hospital) or GP (if at home) immediately. If your GP is unavailable, go straight to the nearest Emergency Department. Early diagnosis and treatment are essential – delay could be very serious or even fatal.

What is the treatment for GBS infection in babies?
Babies with signs of GBS infection should be treated with antibiotics as soon as possible. In most cases GBS infection can be treated successfully with antibiotic therapy and intensive care. Most babies will make a full recovery.

Remember that most infections are preventable by using the treatment approaches mentioned above for women who have risk factors for GBS disease.

What infections can GBS cause in the mother?
GBS may also cause infections in the mother. These include:
• Infection of the membranes and urinary tract infections antenatally or in labour.
• Breast infections, uterine infections, wound infections and urinary tract infections in the postnatal period.

Is there anything else I should know?
No treatment can be guaranteed to work all the time for everyone. Even with antibiotic treatment in labour, some babies will still develop GBS infection.

It is recommended that you breastfeed your baby in the usual way. Breastfeeding has not been shown to increase the risk of GBS infection and may offer benefits to you and your baby.


If you have any questions about GBS or any other health concerns in your pregnancy, please discuss with your Midwife, Obstetrician or GP.

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