Human gut colonisation may be initiated in utero by distinct microbial communities in the placenta and amniotic fluid

Abstract

Interaction with intestinal microbes in infancy has a profound impact on health and disease in later life through programming of immune and metabolic pathways. We collected maternal faeces, placenta, amniotic fluid, colostrum, meconium and infant faeces samples from 15 mother-infant pairs in an effort to rigorously investigate prenatal and neonatal microbial transfer and gut colonisation. To ensure sterile sampling, only deliveries at full term by elective caesarean section were studied. Microbiota composition and activity assessment by conventional bacterial culture, 16S rRNA gene pyrosequencing, quantitative PCR, and denaturing gradient gel electrophoresis revealed that the placenta and amniotic fluid harbour a distinct microbiota characterised by low richness, low diversity and the predominance of Proteobacteria. Shared features between the microbiota detected in the placenta and amniotic fluid and in infant meconium suggest microbial transfer at the foeto-maternal interface. At the age of 3–4 days, the infant gut microbiota composition begins to resemble that detected in colostrum. Based on these data, we propose that the stepwise microbial gut colonisation process may be initiated already prenatally by a distinct microbiota in the placenta and amniotic fluid. The link between the mother and the offspring is continued after birth by microbes present in breast milk.

Exploring the role of the microbiota member Bifidobacterium in modulating immune-linked diseases

“…Briefly, bifidobacteria colonise the new-born gut within the first days and weeks after birth, and they represent the most abundant bacterial family ranging from 40 to 80% of the total gut microbiota [18,19]. There is also evidence to suggest that bifidobacteria could begin colonisation of the GI tract in utero [20,21]; however, this remains controversial as direct proof for microbial colonisation, and the mechanisms by which bacteria pass from the mother to the foetus remain to be elucidated. Current studies indicate that bifidobacteria are transmitted vertically from the mother's vagina, GI tract, or breast milk.…”

Impact of Early-Life Microbiota on the Development of Infants

“…Клеточные структуры кишечных бак-терий выявлены в плаценте и амниотической жидкости до начала родов без разрыва оболочек плодного пузыря [13]. Преобладающие бактерии в меконии -Staphуlococcus и Enterobacteria, при этом обнаружены корреляции между количеством микроорганизмов и сроками гестации [14].…”

Does a prenatal bacterial microbiota exist?

“…4 Recently, maternal-fetal transmission of commensal bacteria and the existence of a placental microbiome have been suggested. [5][6][7][8][9][10] Colonization of the healthy placental and/or fetal tissue with a diverse group of metabolically active bacteria would; however, fundamentally challenge our current thinking of the development of the fetus within a sterile, protected environment. It would require new concepts to explain how bacteria can persist within host tissue but remain anatomically restricted to prevent systemic spread within the fetal organism and how preterm birth, a condition causally linked to bacterial infection of the amniotic tissue, is prevented.…”

“…They concluded the existence of ''microbial transfer at the foeto-maternal interface'' and the presence of a ''fetal microbiota''. 10 A recent PCR-based study on early bacterial airway colonization demonstrated the presence of a diverse and distinct lung microbiome at birth and also hypothesized fetal microbiota acquisition to explain their findings.…”

“…16S rDNA sequencing detected a "low-richness, low-diversity" bacterial composition with a predominance of Proteobacteria. 10 Culture mainly revealed bacteria of the genera Staphylococcus and Propionibacterium (but notably not the known human pathogen S. aureus or any Proteobacteria). They concluded the existence of ''microbial transfer at the foeto-maternal interface'' and the presence of a ''fetal microbiota''.…”