Blood Microbial Communities During Pregnancy Are Associated With Preterm Birth

Abstract

Microbial infection of the placenta, amniotic fluid, vaginal canal, and oral cavity is known to significantly contribute to preterm birth (PTB). Although microbes can be translocated into the blood, little is known regarding the blood microbiota during pregnancy. To assess changes in the microbiome during pregnancy, blood samples were obtained 2 or 3 times during pregnancy from a cohort of 45 pregnant women enrolled between 2008 and 2010. To analyze the association with PTB, we conducted a case-control study involving 41 pregnant women upon admission for preterm labor and rupture of membrane (20 with term delivery; 21 with PTB). Bacterial diversity was assessed in number and composition between the first, second, and third trimesters in term delivered women according to 16S rRNA gene amplicon sequencing, and data were analyzed using Quantitative Insight Into Microbial Ecology (QIIME). Taxonomy was assigned using the GreenGenes 8.15.13 database. Dominant microorganisms at the phylum level in all pregnant women were identified as Firmicutes , Proteobacteria , Bacteroidetes , and Actinobacteria . However, the number and composition of bacteria in women with PTB differed from that in women with term delivery. Firmicutes and Bacteroidetes were more abundant in women with PTB than in women with term delivery, while Proteobacteria was less prevalent in women with PTB. At the genus level, Bacteroides , Lactobacillus , Sphingomonas , Fastidiosipila , Weissella , and Butyricicoccus were enriched in PTB samples. These observational results suggest that several taxa in the maternal blood microbiome are associated with PTB. Further studies are needed to confirm the composition of the blood microbiota in women with PTB. Additionally, the mechanism by which pathogenic microbes in maternal blood cause infection and PTB requires further analysis.

The pelvis urinary microbiome in patients with kidney stones and clinical associations

“…The role of the bladder urinary microbiome in urinary tract disease has recently been revealed using catheterized urine samples [11,22,24,25]. Similarly, an increasing number of studies are exploring the notion that bacteria in human blood do not necessarily equate to infection [15,16,26,27]. The present study explored the existence of the urinary microbiome in the kidney pelvis and its association with the microbiome in the bladder and blood in patients with kidney stones.…”

Association between the sinus microbiota with eosinophilic inflammation and prognosis in chronic rhinosinusitis with nasal polyps

“…EVs circulate through the blood and directly and/or indirectly communicate with tissues and organs 10 . Blood bacterial EVs were suggested to be useful for metagenome analysis of the bodily microbiota in preterm birth and a mouse model of Alzheimer’s disease 41 , 42 . In this study, Deinococcus , Sphingomonas , and Lactobacillus among the sinus bacteria were positively correlated with serum EVs.…”

Gut and Reproductive Tract Microbiota Adaptation during Pregnancy: New Insights for Pregnancy-Related Complications and Therapy

“…Hematogenous spread of microbes with consequent placental colonization has also been proposed as a potential secondary route of invasion and infection leading to PTB [119]. The similarity between the oral and placental microbiome suggests that the placental microbiome becomes colonized primarily as the result of hematogenous bacterial spread via the circulation [120]. However, contradictory data on maternal periodontitis, that could represent an independent risk factor for PTB, is present in the literature.…”