Relationship between maternal Group B Streptococcal colonization and gestational vaginal microbiome composition: A pilot study

Purpose: Group B Streptococcus (GBS) colonization and vaginal microbiome (VMB) dysbiosis are associated with adverse perinatal outcomes. However, the role of GBS colonization in maternal VMB remains unclear. Herein, we aimed to investigate this relationship and identify additional pathogens associated with GBS colonization for potential implications in understanding their clinical significance. Materials and methods: Vaginal swab samples were obtained before delivery from nine women with normal pregnancies for GBS detection and 16S rRNA gene sequencing. The diversity analysis and community state types clustering were used to compare the GBS-positive vs. GBS-negative groups. ANCOM-BC was implemented to identify differentially abundant microbes (DAMs) associated with GBS colonization. The correlation and receiver operating characteristic analysis were used to evaluate the relationship between DMAs and clinical parameters. Results: There were 6/9 (66,7%) GBS-negative pregnant women. The α-diversity index (p ​= ​0.71 for observed operational taxonomic units and p ​= ​0.90 for Shannon diversity), β-diversity index (p ​= ​0.583), and community state types clustering (p ​= ​0.23) were not significantly different between the GBS-positive and -negative groups. Four DAMs, namely, Actinomyces, Shigella, Fenollaria, and Gemella, were significantly associated with GBS colonization, reflecting the dynamicity of the gestational VMB. Their abundances were negatively correlated with birth weight and had acceptable discriminating ability in premature membrane rupture (area under the curve, 0.9). Conclusions: Despite the absence of significant effects on overall VMB composition, our preliminary results investigated that maternal GBS colonization related to high abundance of four pathogens with potential clinical utility as microbial signatures.