Oral Probiotic Supplementation in Pregnancy to Reduce Group B Streptococcus Colonization

Background:

Group B streptococcus (GBS) infection of the newborn is a leading cause of neonatal morbidity and mortality in North America. Up to 30% of pregnant women are colonized with GBS. Half of the babies born to colonized mothers will become colonized themselves, and of those, about 1-2% may develop early onset GBS infection (EOGBS), which is associated with significant mortality (between 5% and 20%) and morbidity (71% bacteremia, 11% meningitis, 19% pneumonia). The current recommendation is for routine administration of IPA to women who test positive for GBS at term. Although IPA therapy may reduce the incidence of neonatal GBS infection, it can increase the risk of other infections such as E. Coli, neonatal thrush, and ampicillin resistant Enterobacteriaceae.

There is also accumulating evidence linking antibiotics in pregnancy with childhood asthma, childhood obesity, and obesity in later life. IPA is also associated with antibiotic resistance, diarrhoea (including Clostridium difficile), and fungal infections. There is a growing worldwide interest in utilizing probiotics to enhance and manipulate the human microbiome in order to reduce a wide range of communicable and non-communicable diseases. Probiotics have been studied extensively in pregnant women and are considered safe and well tolerated when ingested or used vaginally.

Probiotics in pregnancy may reduce GBS colonization and the need for intrapartum antibiotic prophylaxis through a number of mechanisms. Some probiotics produce antibacterial substances and film-like barriers to pathogens. By adhering to vaginal epithelial cells, probiotics also displace pathogens such as GBS. S. salivarius K12 has been shown to inhibit several GBS strains, including disease-implicated isolates from newborns and colonizing isolates from the vaginal tract of pregnant women. In vivo and in vitro studies demonstrate its ability to adhere to the vaginal epithelium and directly impair the growth and adherence of GBS.

Several pilot randomized trials of L. reuteri and L. rhamnosus show promise in their their ability to reduce GBS colonization and have been shown to be safe. In vivo and in vitro studies of various lactobacillus strains, including rhamnosus and reuteri, have demonstrated an inhibitory effect on GBS.