What is Group B Streptococcus (GBS)?
Group B Streptococcus (GBS) is a naturally occurring bacterium that is commonly found in the gastrointestinal and vaginal tracts of healthy adults. While it does not always cause harm, the presence of GBS in the birth canal can lead to infections in newborns. One emerging area of interest in managing GBS colonization is the role of probiotics— beneficial bacteria that support a healthy microbiome.
Screening for GBS and Mitigating Risks
GBS can be present in 10-30% of pregnant people. Most adults do not have symptoms, but it can pose serious complications to newborns, such as neonatal sepsis, pneumonia and meningitis if transmitted during childbirth.
To mitigate risks, pregnant people are typically screened for GBS, via vaginal and rectal swab culture, between 35 and 37 weeks of pregnancy. Those who test positive are often given antibiotics during labor to prevent transmission.
If a pregnant GBS carrier is not treated with IV antibiotics during labour, the newborn has a 1-2% risk of developing a severe early-onset GBS infection within the first week of life; with IV antibiotic treatment, the risk drops to 0.2%.
However, antibiotic use can disrupt the natural microbiome, leading to imbalances that may increase susceptibility to digestive discomfort or other infections, such as yeast infections or antibiotic-resistant bacteria. This has led to growing interest in probiotics to reduce GBS colonization naturally.
The Role of Probiotics in Managing GBS
Probiotics are beneficial bacteria that support gut and vaginal health by promoting a balanced microbiome. Certain probiotic strains, particularly Lactobacillus species, have shown promise in reducing the presence of harmful bacteria, including GBS. Research suggests that, Lactobacillus rhamnosus and Lactobacillus reuteri may help maintain a vaginal environment less conducive to GBS colonization.
Potential Mechanisms of Probiotics Against GBS
Probiotics may help manage GBS colonization through several mechanisms:
- Competitive Exclusion: Beneficial bacteria compete with GBS for space and nutrients, making it harder for GBS to establish itself.
- Production of Antimicrobial Substances: Some probiotic strains produce acids, bacteriocins, and hydrogen peroxide, which can inhibit the growth of GBS.
- Modulation of the Immune System: Probiotics may enhance immune function, helping the body naturally suppress GBS overgrowth.
- Restoration of Microbial Balance: By supporting a healthy vaginal microbiome, probiotics can help reduce the likelihood of GBS over colonization.
Evidence from Research
Studies on the effectiveness of probiotics in reducing GBS colonization have shown mixed results. Some research indicates that probiotic supplementation, particularly with Lactobacillus strains, may reduce vaginal GBS colonization rates, while other studies suggest that more extensive research is needed to confirm these findings. Probiotics are generally considered safe and may serve as a complementary approach alongside traditional antibiotic treatments.
How to Use Probiotics for GBS Prevention
If considering probiotics for GBS management, the following tips may be helpful:
- Choose the Right Strains: Look for probiotic supplements containing L. rhamnosus and L. reuteri.
- Use High-Quality Supplements: Look for reputable brands with clinically tested strains, guaranteed live cultures and high colony-forming units (CFUs).
- Choose the Right Route of Administration: Both oral and vaginal suppository probiotics are options for treatment.
- Consider Dietary Sources: Fermented foods such as yogurt, kefir, and sauerkraut naturally contain beneficial bacteria.
- Consult a Healthcare Provider: Always discuss probiotic use with a doctor, midwife or naturopathic doctor, especially during pregnancy. Through informed decision-making, your healthcare provider will be able to provide additional recommendations on the product that is right for you based on GBS carrier status and any additional risk factors.
While prophylactic antibiotics remain the primary method and standard of care for preventing GBS transmission during childbirth, probiotics offer a potential complementary approach by promoting a healthy vaginal microbiome. Research on probiotics for GBS is ongoing, but early findings suggest they may play a role in reducing colonization and supporting overall microbial balance. Pregnant women interested in probiotic use should consult their healthcare providers to ensure safety and effectiveness.
References
Ho, M., Chang, Y., Chang, W., & Lin, H. (2016). “Use of Lactobacillus probiotics to prevent Group B Streptococcus colonization: A systematic review and meta-analysis.” Journal of Maternal-Fetal & Neonatal Medicine, 29(24), 4005-4012. doi:10.3109/14767058.2015.1137892
Ho, M., Chang, Y., Chang, W., Wang, M., Lin, W., Chiu, T. (2016). “Oral Lactobacillus rhamnosus GR-1 and Lactobacillus Reuters RC-14 to reduce Group B Streptococcus colonizization in pregnant women: A randomized controlled trial.” Taiwanese Journal of Obstetrics and Gynaecology, 55, 515-518. doi: 10.1016/j.tjog.2016.06.003
Kostovska, M., Kukurozović, M., & Zegura, B. (2020). “The role of probiotics in the prevention of Group B Streptococcus colonization in pregnant women.” BMC Pregnancy and Childbirth, 20(1), 578. doi:10.1186/s12884-020-03258-1
Martinez, R. C., Franceschini, S. A., Patta, M. C., Quintana, S. M., & Reid, G. (2008). “Improved colonization of Lactobacillus rhamnosus GR-1 in the vaginal environment after oral administration of probiotics.” Applied and Environmental Microbiology, 74(14), 4315-4321. doi:10.1128/AEM.02698-07
Morwood, J., Hutton, J., & Thornton, S. (2019). “Probiotics and Group B Streptococcus: A randomized controlled trial in pregnancy.” British Journal of Obstetrics and Gynaecology, 126(7), 885-892. doi:10.1111/1471-0528.15776
Sharpe, M., Shah, V., Freire-Lizama, T., Cates, E. C., McGrath, K., David, I., … Stewart-Wilson, E. (2019). Effectiveness of oral intake of Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 on Group B Streptococcus colonization during pregnancy: a midwifery-led double-blind randomized controlled pilot trial. The Journal of Maternal-Fetal & Neonatal Medicine, 34(11), 1814–1821. doi.org/10.1080/14767058.2019.1650907
