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The Uterine Microbiota
Published in Carlos Simón, Carmen Rubio, Handbook of Genetic Diagnostic Technologies in Reproductive Medicine, 2022
Jonah Bardos, Carlos Simón, Inmaculada Moreno
Studies have found that different gynecological conditions are associated with different microbiota. Infertility has been associated with increased abundance of Atopobium, Pelomonas, and Sneathia, among many other genera.58 Chronic endometritis (CE) is typically defined as a chronic inflammation of the uterine lining and is associated with the presence of plasma cells following endometrial biopsy.59,60 Multiple studies have suggested that chronic endometritis is associated with recurrent pregnancy loss.61,62Numerous microbes have been found in patients with CE, including Neisseria gonorrhea, Gardnerella vaginalis, Chlamydia trachomatis, Escherichia coli, Streptococcus spp., Staphylococcus spp., and Enterococcus faecalis and non-microbial causes such as retained tissue. Additionally, endometriosis has been hypothesized to alter the endometrium through increased inflammation and progesterone resistance which can affect implantation, increase the risk of miscarriage, and result in poor pregnancy outcomes, including pregnancy-induced hypertension and preterm birth.63 It would appear that, regardless of the cause, increased inflammation at the endometrial level may affect implantation and pregnancy outcomes.
The meconium microbiota shares more features with the amniotic fluid microbiota than the maternal fecal and vaginal microbiota
Published in Gut Microbes, 2020
Qiuwen He, Lai-Yu Kwok, Xiaoxia Xi, Zhi Zhong, Teng Ma, Haiyan Xu, Haixia Meng, Fangqing Zhao, Heping Zhang
Hitherto, Stinson et al. have been the only published study that applied PacBio sequencing to describe the microbiota of meconium and amniotic fluid samples of maternal-neonate pairs.16 Large differences were observed in the microbiota composition of the meconium and amniotic fluid samples between this study and Stinson et al. The discrepant results could be due to both an additional PCR decontamination step (using a double-strand specific DNase) in Stinson et al. and natural inter-ethnic/-individual variations in the microbiota composition. The incorporation of such decontamination step could minimize the risk of contamination from reagent kits, but meanwhile increased the chance of accidental removal of template DNA, compromising the microbiota diversity. Nevertheless, Stinson et al. and the current study identified 15 common meconium-associated species and 25 common amniotic fluid-associated species (Table S5), suggesting commonalities in the microbiota composition of samples collected from independent sources. Stinson et al. found that most meconium microbiota contained abundant Pelomonas puraquae sequences, and there was an intense negative correlation between the number of Pelomonas puraquae reads and the propionate level in the meconium samples, strongly suggesting that this species had true biological significance.16 In the current dataset, Pelomonas puraquae sequences were detected in only five amniotic fluid samples, but Pelomonas saccharophila sequences were found in 13 meconium, 28 amniotic fluid, 18 vaginal fluid, three maternal feces, and one saliva samples (Table S6). Ten of the 13 Pelomonas saccharophila sequence-positive meconium samples also had Pelomonas saccharophila sequences in their amniotic fluid and/or vaginal fluid counterparts. Conversely, even Pelomonas saccharophila sequences were detected in three maternal feces and one saliva samples, their meconium counterparts were Pelomonas saccharophila sequence-negative. Our data supported that Pelomonas was a part of the meconium microbiota, and this species might be seeded from the amniotic fluid and/or vaginal tract microbiota.