Vaginal microbiome during and after pregnancy

In healthy reproductive-aged women, the vaginal microbiome is generally dominated by members of the Lactobacillus genus, able to promote the maintenance of the vaginal eubiosis, preventing the colonization and growth of adverse microorganisms. The depletion of lactobacilli, combined with the increase of different species of anaerobic bacteria, can result in the switch from a normal vaginal ecosystem to a polymicrobial dysbiosis known as bacterial vaginosis (BV). It is well known that the vaginal bacterial composition plays a crucial role in maternal-fetal health: indeed, a condition of vaginal dysbiosis and its related bacterial taxa are associated with several pregnancy complications and preterm birth. Moreover, during delivery, the composition of the vaginal ecosystem can impact on newborn's health, shaping the development of the infant's bacterial communities, and modulating the risk of disease susceptibility later in life. On the other hand, it is known that the inhabitants of the vaginal microbiome can harbor several genetic determinants conferring antimicrobial resistance. Among them, the ribosome protection type of tetracycline (i.e., tet genes) and the methylase type erythromycin resistance genes (i.e., erm genes) represent the most common ones. Thus, studying the distribution of macrolide and tetracyclines resistance genes and their association with vaginal bacterial communities in pregnant women could open new perspectives for the management of pregnancy and the care of newborn health. Therefore, this study, aims at the characterization of the vaginal microbiome of Caucasian women at different gestational ages and during the puerperium, for a total of 228 samples (72 first trimester, 63 second and third trimester, 30 during puerperium). Moreover, we assessed the presence of two markers of macrolide resistance, ermB and ermF, as well as two determinants of tetracycline resistance, tet(W) and tet(M), in the vaginal environment and related them to the characteristics of the vaginal microbiome in terms of bacterial composition (sequencing of bacterial 16S rRNA gene).