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Group B Strep


•All pregnant women at 35 to 37 weeks of pregnancy are screened for GBS colonization and all GBS positive women are treated with antibiotics in labour or at the time of membrane rupture. This evidence suggests that the universal screening approach is over 50% more effective than the risk-based approach at preventing transmission to the newborn.

•There is evidence that self-collection of swabs by pregnant women, with appropriate instruction, in the clinic examination room or washroom, is as effective as collection by caregivers.

Instructions on collecting a GBS swab:

  • A single swab is taken from the lower third of the vagina and then the anorectum (through the anal sphincter). Failure to swab the anorectum is associated with a significant false negative rate.
  • Women found to have GBS in the urine in any concentration are regarded as colonized at delivery. They do not require further GBS screening and should receive antibiotic prophylaxis in labour.
  • There is no benefit in treating women with positive GBS vaginal cultures prior to labour or membrane rupture.
  • screen planned c-section in case rupture of membranes occurs or labour as would then be treated.

Current Recommendations:

1. Treat with antibiotics at the time of membrane rupture or labour for all women who have had:

  • Previous infant with invasive GBS disease
  • GBS urine during current pregnancy (regardless of whether treated due to symptoms or high concentration)
  • Positive screening culture, routinely done at 35–37 weeks during current pregnancy.

If GBS status is unknown, treat with antibiotics for any of the following:

  1. Preterm labour (< 37 weeks)
  2. Rupture of membranes for > 18 hours
  3. Maternal fever ≥ 38ºC.

2.Preterm labour with intact membranes:

  • If GBS status negative within five weeks, antibiotics need not be initiated.
  • If GBS status unknown, GBS vaginal/rectal screening should be performed on admission and antibiotics started pending results of culture. Antibiotics may be stopped if culture is negative.

3.Management of prelabour rupture of membranes:

  • For women with term PROM who are colonized with GBS, it is recommended that labour be induced with oxytocin.


ALARM 2014

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