Group B Streptococcus – What is It & What Should You Know

December 11, 2021

What is Group B Streptococcus (GBS)

Group B strep is a bacteria that is commonly found in the human gut /genital and urinary tract (in up to 30% of people). It is related to, but not the same as Group B streptococcus (GBM), which occurs mainly in the throat. Many of us live with or carry GBS bacteria without knowing it.
This bacterium usually causes no symptoms in people with healthy immune systems.

Group B Streptococcus

Group B Streptococcus & Pregnancy

Approximately 20% of all pregnant women carry Group B Streptococcus (GBS) in their vaginas at the time of birth. GBS colonization in the vagina is asymptomatic and rarely causes any maternal complications but can cause a very serious infection acquired by newborns before or during birth.

Group B Streptococcus (GBS) infections have been associated with early miscarriage, premature rupture of membranes, stillbirth & neonatal death.

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GBS and the Newborn

Due to the immature immune systems of many newborn babies, Group B Streptococcus (GBS) disease occurs in 0.5 per 1000 babies, and causes illnesses such as meningitis, pneumonia and/or sepsis. Two percent of infected babies will die.

Risk Factors for Neonatal Group B Streptococcus Disease

  • Preterm labour (less than 37 weeks)
  • Rupture of membranes for greater than 18 hours
  • Maternal fever in labour
  • GBS bacteria found in urine anytime in this pregnancy
  • History of a previous baby that developed GBS disease

Group B Streptococcus Screening and Treatment The current recommendation for the prevention of GBS disease is that all pregnant women are offered a vaginal-rectal swab between 35-37 weeks. Since GBS colonization can come and go, testing within five weeks of the due date is shown to be predictive of GBS status at the time of birth.

If the mother is GBS colonized Penicillin Is offered in labour or with the onset of her water breaking (whichever is sooner).

Give me the stats!
About 50% of babies born through untreated GBS will become colonized (not infected)
About 1-2% of babies born through untreated GBS will become seriously ill. (Infected)
If the mother is treated for GBS in labour with antibiotics the risk of newborn GBS illness decreases by 80%. (It’s effective)
2-3% of term babies who develop GBS infection will die.
20-30% of preterm babies who develop GBS infection will die.


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