Integrated metagenomics and metabolomics analysis of third-trimester pregnant women with premature membrane rupture: a pilot study

BACKGROUND: Premature rupture of membranes (PROM) is a major pregnancy complication in China and usually leads to adverse pregnancy outcomes. The major aim of this study was to search for microorganisms and their related metabolites that have direct relationship with PROM. METHODS: For vaginal discharge samples, metagenomics sequencing was applied to identify microorganisms that were enriched in PROM subjects, and untargeted metabolomics was applied to characterize the metabolites changes in PROM subjects compared to healthy controls (HC). Correlation analysis was then used to explore the relationship between these microorganisms and metabolites changes. RESULTS: Two upstream metabolites of glycolysis, N-acetyl-D-galactosamine (GalNAc) and sucrose, were found downregulated in the PROM group (P=0.04 and P=0.041, respectively). Higher percentages of conditional pathogens, such as of Streptococcus (8.4% vs. 6.1% in HC group, P=0.15) and Chlamydia (4.3% vs. 2.3% in HC group, P=0.07) were found in PROM group. Other common conditional pathogens including Prevotella, Staphylococcus, Mycobacterium and Enterobacter, were also higher in PROM group, although their absolute percentages were low and the differences did not reach statistical significance due to relative small sample size. Correlation analysis further demonstrated a positive correlation of downregulation of glycolysis metabolites with higher percentage of conditional pathogens. CONCLUSIONS: Integrated metagenomics and metabolomics analysis can be used to track the subtle changes in the vaginal microenvironment. Downregulation of glycolysis substrates (GalNAc and sucrose) and increase of related pathogenic microorganisms (Streptococcus and Chlamydia) could serve as early warning biomarkers of PROM.