Group B Streptococcus (GBS) is the most common cause of life-threatening infections in newborn babies in the UK.

What is Group B Streptococcus (GBS)?

Group B Streptococcus is the commonest cause of life-threatening infections in newborn babies in the UK. Most GBS infections can be prevented by giving antibiotics intravenously (through a vein) at the onset of labour to all women where GBS been detected during their current pregnancy. It is also appropriate for those with other recognised risk factors (having previously had a baby with GBS, having a fever in labour, labour starting, or waters breaking before 37 completed weeks of pregnancy and/or waters breaking more than 18 hours before delivery). This recommended use of antibiotics reduces the likelihood of early-onset GBS infection developing in a baby born to a woman carrying GBS at the time of delivery from around 1 in 300 to less than 1 in 6000.

Intravenous antibiotics given in labour are highly effective at preventing GBS infection in newborn babies. Oral antibiotics should not be given during pregnancy for GBS colonisation as they have not been shown to be effective. There are always small but potentially serious risks associated with taking antibiotics, and management and treatment need to be fully discussed.

Detecting a GBS carrier

Screening for GBS carriage is not routinely offered in the NHS. Laboratory testing of GBS testing is routinely undertaken at The Doctors Laboratory. The method for testing is an enriched culture medium (ECM) specifically designed for the isolation of GBS in swabs. Two swabs (lower vaginal and rectal) need to be cultured, ideally in the last five weeks of pregnancy, to best predict colonisation of GBS around the time of delivery.
Group B Strep Awareness Month

The facts concerning GBS

GBS is the most common cause of serious infection in newborn babies in the UK. Without preventative medicine, around 1 in 1000 babies in the UK would develop a GBS infection i.e. about 700 babies a year. Babies are usually exposed to GBS shortly before or during birth. It is not understood why some babies are susceptible to the bacteria and develop infection, whilst others do not. What is clear, however, is that most GBS infections in newborn babies can be prevented by giving intravenous antibiotics from the onset of labour until the baby is born to women whose babies are at higher risk.

What should be done next?

Testing for GBS needs to be included in the pregnancy and birth plan and discussed with the midwife, Obstetrician or GP with an understanding of what should happen if GBS is isolated. UK guidelines recommend that, when GBS is detected during the current pregnancy, the woman should be offered intravenous antibiotics in labour. This will stop most GBS infections from developing in newborn babies.

Procedure for testing

Testing for GBS needs to be undertaken between 35-37 weeks or ideally in the last few weeks of a pregnancy. Two swabs need to be taken and accompanied by a completed request form showing:

  • Patient's name, address and date of birth. Please provide the address to where results are to be sent).
  • Mobile phone number is you would like to receive results by text message.
  • Name and full address, phone and or fax number of Midwife and/or Obstetrician to whom results will be sent. 
  • Gestation (weeks).
  • Complete payment details (credit/debit card/cheque - made payable to The Doctors Laboratory.

Taking the sample

Label swab tubes correctly by writing:

  • Name, date of birth, location of each swab (lower vaginal without speculum, or rectal).

Lower vaginal swab:

  • Remove blue capped swab from packet.
  • Remove the white cap from the transport medium tube and throw away.
  • Insert swab into lower vagina by not more than 2-4 cm. A speculum should not be used.
  • Rub lower vagina gently with swab, round the front, sides and back of vagina.
  • Withdraw swab and place into transport medium provided by The Doctors Laboratory. Ensure the blue cap is sealed securely.

Rectal Swab:

  • Remove blue capped swab from packet.
  • Remove the white cap from the transport medium tube and throw away.
  • Insert swab gently into the anus so that not more than 1-2 cm of the swab is in the rectum.
  • Withdraw swab and place in transport medium in the tube provided by The Doctors Laboratory. Ensure the blue cap is sealed securely.
  • Ensure both swabs are labelled with your full name and date of birth.

The swabs and request form need to be sent to Medlab Pathology in the post-paid reply envelope provided. The result of the test will be available within 3 working days of receipt of swabs. Results will be sent both to the patient and to the referring healthcare professional showing whether GBS has been isolated (positive) or not (not-isolated).

Cost of GBS Screen

£40.00  (this includes the request form, postal pathology pack, 2 swabs in non-nutritive transport medium, post paid padded envelope and laboratory testing service).

How to request GBS Screening Pack(s)

Please contact the MedLab Pathology  on free-phone 1800 303 349 (ROI) or 0808 234 0925 (NI) for instructions on requesting GBS Screening Pack(s)

For more information on GBS please contact:

Group B Strep Support, PO Box 203, Haywards Heath, West Sussex RH16 1GF
Tel: 01444 416176 E-mail: Website:
Registered charity No 1058159

Group B Strep Support is a national charity providing accurate and up
to date information on GBS for families and health professionals. Group B Strep Support endorses the availability of reliable prenatal GBS testing but has no particular links with nor receives any money from any laboratory. GBSS wants to see reliable testing for GBS routinely available to all pregnant women on the NHS. All the charity's current leaflets are available from their website or by post.

Key medical references
NICE. Antibiotics for early-onset neonatal infection: Antibiotics for the prevention and treatment of early-onset neonatal infection (CG149).
National Institute for Clinical Excellence Guidelines. 2012.
RCOG. The Prevention of Early Onset Neonatal Group B Streptococcal Disease (2nd edition). Royal College of Obstetricians and Gynaecologists Guidelines 36. 18-7-2012.
Health Protection Agency. Processing Swabs for Group B Streptococcal Carriage (UK Standards for Microbiology B 58). 2012.
Centers for Disease Control and Prevention. Prevention of Perinatal Group B Streptococcal Disease - Revised Guidelines from CDC: 2010. MMWR Reports & Recommendations 59 (2010).