Prenatal antibiotic treatment does not decrease group B streptococcus colonization at delivery

Int J Gynaecol Obstet. 2008 May;101(2):125-8. doi: 10.1016/j.ijgo.2007.10.012. Epub 2007 Dec 20.


Objective: To evaluate whether an outpatient antibiotic regimen decreased group B streptococcal (GBS) colonization to preclude the use of intrapartum antibiotics.

Methods: A double-blind randomized controlled trial evaluating prenatal oral amoxicillin versus placebo with the primary outcome of GBS colonization at the time of labor.

Results: Of those patients receiving both amoxicillin and a repeat culture at the time of labor, 6 of the 14 (43%) tested positive for GBS colonization. Given persistent GBS colonization of 67% (10/15) in the placebo group, treatment with amoxicillin did not significantly impact colonization at the time of delivery (P=0.20).

Conclusion: A regimen of outpatient amoxicillin was associated with persistent GBS colonization in 43% of women at the time of labor. Oral prenatal antibiotic prophylaxis against GBS does not sufficiently reduce colonization to preclude intrapartum intravenous antibiotics.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Ambulatory Care
  • Amoxicillin / therapeutic use*
  • Anti-Bacterial Agents / therapeutic use*
  • Antibiotic Prophylaxis*
  • Delivery, Obstetric
  • Double-Blind Method
  • Female
  • Humans
  • Infant, Newborn
  • Infectious Disease Transmission, Vertical / prevention & control
  • Pregnancy
  • Pregnancy Complications, Infectious / diagnosis
  • Pregnancy Complications, Infectious / prevention & control*
  • Prenatal Care
  • Streptococcal Infections / diagnosis
  • Streptococcal Infections / prevention & control*
  • Streptococcal Infections / transmission
  • Streptococcus agalactiae / isolation & purification*


  • Anti-Bacterial Agents
  • Amoxicillin