Cervical pessary and cerclage placement for preterm birth prevention and cervicovaginal microbiome changes

Is the Early Screening of Lower Genital Tract Infections Useful in Preventing Adverse Obstetrical Outcomes in Twin Pregnancy?

Objectives: Twin pregnancy implies a higher risk of preterm birth and, consequently, higher neonatal morbidity and mortality. In singleton pregnancies, infections of the lower genital tract (LGTIs) and bacterial vaginosis are associated with preterm labor, and their early detection has been proven effective in reducing complications like the preterm premature rupture of membranes (pPROM) and preterm delivery. The same evidence, however, is lacking for twin pregnancies. This study aimed to evaluate whether the early identification and treatment of LGTIs or bacterial vaginosis in asymptomatic women with twin pregnancy could reduce the rate of miscarriages, pPROM, and preterm birth. Methods: This study performed a retrospective comparison of 285 women with a multiple pregnancy submitted for a cervico-vaginal swab only at 20-22 weeks (Single Test Group, STG), and 199 women who underwent the swab at 12-14 and again at 20-22 weeks (Double Test Group, DTG). All women included in the study had a twin pregnancy and were followed up at Sant'Anna Hospital, Turin (Italy), between September 2012 and February 2021. Results: In STG, 21.7% of patients had a positive swab; in DTG, 19.9% had an early positive swab that was immediately treated by targeted antibiotics; and 16.7% had a mid-pregnancy positive swab. The DTG showed a significantly lower incidence of pPROM in univariate analysis (14.4% vs. 23.1%, p = 0.021), which was confirmed by multivariate analysis (OR 0.55, CI 0.33-0.93, p = 0.025). Conclusions: Our study suggests that, in asymptomatic women with twin pregnancy, the early screening of LGTIs and bacterial vaginosis by a cervico-vaginal swab at 12-14 weeks of gestational age is effective in reducing the risk of pPROM.

GSR-DB: a manually curated and optimized taxonomical database for 16S rRNA amplicon analysis

Amplicon-based 16S ribosomal RNA sequencing remains a widely used method to profile microbial communities, especially in low biomass samples, due to its cost-effectiveness and low-complexity approach. Reference databases are a mainstay for taxonomic assignments, which typically rely on popular databases such as SILVA, Greengenes, Genome Taxonomy Database (GTDB), or Ribosomal Database Project (RDP). However, the inconsistency of the nomenclature across databases and the presence of shortcomings in the annotation of these databases are limiting the resolution of the analysis. To overcome these limitations, we created the GSR database (Greengenes, SILVA, and RDP database), an integrated and manually curated database for bacterial and archaeal 16S amplicon taxonomy analysis. Unlike previous integration approaches, this database creation pipeline includes a taxonomy unification step to ensure consistency in taxonomical annotations. The database was validated with three mock communities, two real data sets, and a 10-fold cross-validation method and compared with existing 16S databases such as Greengenes, Greengenes 2, GTDB, ITGDB, SILVA, RDP, and MetaSquare. Results showed that the GSR database enhances taxonomical annotations of 16S sequences, outperforming current 16S databases at the species level, based on the evaluation of the mock communities. This was confirmed by the 10-fold cross-validation, except for Greengenes 2. The GSR database is available for full-length 16S sequences and the most commonly used hypervariable regions: V4, V1-V3, V3-V4, and V3-V5.IMPORTANCETaxonomic assignments of microorganisms have long been hindered by inconsistent nomenclature and annotation issues in existing databases like SILVA, Greengenes, Greengenes2, Genome Taxonomy Database, or Ribosomal Database Project. To overcome these issues, we created Greengenes-SILVA-RDP database (GSR-DB), accurate and comprehensive taxonomic annotations of 16S amplicon data. Unlike previous approaches, our innovative pipeline includes a unique taxonomy unification step, ensuring consistent and reliable annotations. Our evaluation analyses showed that GSR-DB outperforms existing databases in providing species-level resolution, especially based on mock-community analysis, making it a game-changer for microbiome studies. Moreover, GSR-DB is designed to be accessible to researchers with limited computational resources, making it a powerful tool for scientists across the board. Available for full-length 16S sequences and commonly used hypervariable regions, including V4, V1-V3, V3-V4, and V3-V5, GSR-DB is a go-to database for robust and accurate microbial taxonomy analysis.

Microenvironment of the Lower Reproductive Tract: Focus on the Cervical Mucus Plug

The female lower reproductive tract microbiota is a complex ecosystem comprising various microorganisms that play a pivotal role in maintaining women's reproductive well-being. During pregnancy, the vaginal microbiota undergoes dynamic changes that are important for a successful gestation. This review summarizes the implications of the cervical mucus plug microenvironment and its profound impact on reproductive health. Further, the symbiotic relationship between the vaginal microbiome and the cervical mucus plug is highlighted, with a special emphasis on how this natural barrier serves as a guardian against ascending infections. Understanding this complex host-microbes interplay could pave the way for innovative approaches to improve women's reproductive health and fertility.