Group B Streptococcus

Posted on March 1, 2012 - 4:40pm
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Updated March 2016.


What is group B strep? (GBS)

Group B streptococcus, also commonly known as group B strep or GBS, is a naturally occurring bacterium that resides in the lower intestines of up to a third of all healthy adults, and in the vaginas and rectum of up to a third of all healthy adult women.

GBS bacteria are normally harmless, and as such, the majority of women carrying GBS will not have any symptoms, or even know that they carry the bacteria until they are tested. It is important to note that GBS is not sexually transmitted, nor is it a sign of poor hygiene.

Unborn babies can acquire GBS in-utero, or via the genital tract during labour or birth. It is not fully understood why only a small percentage of babies become ill due to the presence of this bacteria. Approximately 50% of mothers carrying GBS will pass on the bacteria, however; only approximately 1-2% of babies will develop an associated infection.


Why do we test for GBS in Pregnancy?

According to Royal Australia New Zealand College of Obstetrics and Gynaecology, GBS was found to be the primary cause of early onset of neonatal sepsis in the 1970’s.  Research showed, that if left untreated, approximately one in every 200 babies born to women who carried GBS went on to develop neonatal sepsis. Neonatal sepsis is categorised as either early onset, which is most common (within 24 hours of birth), or late onset (7 days to 3 months after birth). Symptoms associated with neonatal sepsis include respiratory problems, bacteraemia, pneumonia and meningitis. Complications associated with neonatal sepsis can result in death.

So, whilst infection in babies is not common, even for women that do carry GBS, the outcome of a GBS infection can be severe, therefore conservative management is the best option.

In the early 1990’s antenatal screening for GBS was introduced, and more recently, the test has become a routine part of antenatal testing.


Testing for GBS, and new best practice in 2016.

Around 36 weeks of pregnancy, Dr Morris will perform a low vaginal and anal swab to test for the presence of GBS. If you are found to be positive for the bacteria, you will be treated with antibiotics during labour.  If you know you are GBS positive, and your membranes rupture, go straight to the hospital to which you are booked. You will be treated with antibiotics once you are admitted. If you are in labour and your membranes have not ruptured, go to the hospital as normal and the midwives there will know when to commence treatment. The antibiotics will be given in 6 hourly doses, or if it is a short labour, antibiotic just needs to be given half an hour before the baby is born.

If you have any further questions in relation to GBS, please discuss with Dr Morris at your next visit.

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GBS   GBS in pregnancy   group B Strep   Group B streptococcus   Group B streptococcus in pregnancy  
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