Group B Streptococcus and the Vaginal Microbiome among Pregnant Women: a
Systematic Review
Abstract
Background: Current analysis methods of the vaginal microbiome often
fail to identify and/or report known pathogens such as S. agalatiae
(GBS), resulting in an incomplete clinical understanding of bacterial
composition during pregnancy. Objective: To determine the frequency of
GBS reporting in vaginal microbiome literature pertaining to pregnancy
and examine methodological bias that contributes to differences in
species and genus-level microbiome reporting. Search strategy: PubMed,
CINAHL, and Web of Science databases were used to identify papers for
review based on the search terms “vaginal microbiome”, “pregnancy”,
and “16S rRNA sequencing”. Selection criteria: Forty-five research
articles reported employing a metagenomic approach for vaginal
microbiome analysis during pregnancy that explicitly reported taxonomic
composition and were included in this review. Data collection and
analysis: Articles were evaluated for methods of DNA extraction and
sequencing, 16S region, taxonomy classification database, number of
participants or vaginal specimens, and pregnancy trimester. Main
results: Less than 30% of articles reported the presence of GBS. No
significant differences in methodology were identified between articles
that reported versus did not report GBS. However, large variability
across the types of research methods used for vaginal microbiome
analysis and species-level bacterial community reporting were observed.
Conclusion: Considerable differences in study design and data formatting
methods may contribute to underrepresentation of GBS, and other known
pathogens, in existing vaginal microbiome literature. Providing detailed
methods, analysis code and raw data may improve reproducibility and
ability to compare microbial communities across studies. Keywords:
vaginal microbiome, pregnancy, 16S ribosomal RNA, whole genome
sequencing, Group B Streptococcus