Vaginal microbiome profiles of pregnant women in Korea using a 16S metagenomics approach

Problem: The stability and dominance of Lactobacillus spp. in vaginal fluid are important for reproductive health. However, the characterization of the vaginal microbiota of women with preterm labor (PTL) or preterm premature rupture of membranes (P-PROM), and its association with preterm birth (PTB) are poorly understood. Method of study: We collected vaginal fluid from women at risk of PTB (n = 58) in five university hospitals in Korea. We performed a hierarchical clustering analysis and classification according to the Lactobacillus spp. and Lactobacillus abundance using Illumina MiSeq sequencing of 16S rRNA gene amplicons. Results: Women at risk for PTB caused by P-PROM had greater bacterial richness and diversity at the time of admission than those with PTL (P < 0.05). However, they were not significantly different between term and preterm samples. In the classification by Lactobacillus spp., the community commonly dominated by Bacteroides and Lactobacillus crispatus was found for the first time in pregnant women in Korea, and all women with this community delivered preterm. Intriguingly, women with an abundance of Weissella in a Bacteroides-dominant community delivered at term. Moreover, in the classification by Lactobacillus proportion, the abundances of Weissella and Rickettsiales were associated with term deliveries, but the abundances of Bacteroides and Escherichia-Shigella were associated with PTBs (P < 0.05). Conclusion: This result suggests that Lactobacillus abundance-based classification of vaginal fluid may reveal the microbiome associated with PTB. Further studies are needed to investigate the mechanism underlying the link between the microbiome and PTB.