Group B Streptococcus (GBS) Infections Guidelines

Updated: Apr 21, 2021
  • Author: Christian J Woods, MD, FACP, FCCP, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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GBS Prophylaxis in Preterm Labor

 The American College of Obstetricians and Gynecologists has updated guidelines on the prevention of early-onset GBS infection in newborns, which have replaced the third set of GBS prevention guidelines from the Centers for Disease Control and Prevention published in 2010. [3, 4]

In summary, the recommendations are to perform a universal GBS screening between weeks 36 0/7 and 37 6/7 of gestation, regardless of the planned mode of delivery. This provides a 5-week window for valid cultures, which increases the accuracy of predicting GBS colonization status at the time of delivery. [24, 25, 26]  Screening is best done with vaginal-rectal cultures. For patients with positive cultures, it is best to offer early intrapartum intravenous antibiotics because 2 hours of antibiotic administration has been shown to be effective in decreasing the frequency of neonatal sepsis by decreasing the GBS vaginal colonies. [27]

For prevention of early-onset GBS infection, penicillin G remains the agent of choice. For women with penicillin allergy in whom the risk for anaphylaxis is considered to be low and/or in whom the severity of a reaction is uncertain, first-generation cephalosporins can be used. For women with penicillin allergy in whom the risk for anaphylaxis is high, penicillin allergy testing should be performed, if available, and cultures should include testing for susceptibility to clindamycin. Intravenous vancomycin remains the agent of choice for patients with high-risk penicillin allergy and also for those with GBS isolates not susceptible to clindamycin.

The following scenarios are indications for intrapartum prophylaxis:

  • Maternal history of delivery of a neonate with invasive GBS disease
  • Positive GBS cultures obtained at 36 0/7 weeks of gestation or later during pregnancy
  • GBS bacteriuria during any trimester of current pregnancy
  • Unknown GBS status at onset of labor and any of the following:

            -Delivery before 37 0/7 weeks of gestation

            -Amniotic rupture of membranes 18 hours or more before delivery

            -Maternal fever (≥38 °C) during labor

            -Positive result of nucleic amplification testing for GBS

            -Negative result of nucleic amplification testing   for GBS but patient has 1 of the first 3 risk factors listed

  • Known GBS-positive status in a previous pregnancy.

Intrapartum antibiotics are not required for GBS carriers who are having a planned cesarean delivery with intact membranes and no labor. [28]