Mueller Noel T, Shin Hakdong, Pizoni Aline, Werlang Isabel C, Matte Ursula, Goldani Marcelo Z, Goldani Helena A S, Dominguez-Bello Maria G
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
Welch Center for Prevention, Epidemiology and Clinical Research, Baltimore, MD 21205, USA.
Genes (Basel). 2017 Dec 4;8(12):364. doi: 10.3390/genes8120364.
Cesarean (C-section) delivery, recently shown to cause excess weight gain in mice, perturbs human neonatal gut microbiota development due to the lack of natural mother-to-newborn transfer of microbes. Neonates excrete first the in-utero intestinal content (referred to as meconium) hours after birth, followed by intestinal contents reflective of extra-uterine exposure (referred to as transition stool) 2 to 3 days after birth. It is not clear when the effect of C-section on the neonatal gut microbiota emerges. We examined bacterial DNA in carefully-collected meconium, and the subsequent transitional stool, from 59 neonates [13 born by scheduled C-section and 46 born by vaginal delivery] in a private hospital in Brazil. Bacterial DNA was extracted, and the V4 region of the 16S gene was sequenced using the Illumina MiSeq (San Diego, CA, USA) platform. We found evidence of bacterial DNA in the majority of meconium samples in our study. The bacterial DNA structure (i.e., beta diversity) of meconium differed significantly from that of the transitional stool microbiota. There was a significant reduction in bacterial alpha diversity (e.g., number of observed bacterial species) and change in bacterial composition (e.g., reduced Proteobacteria) in the transition from meconium to stool. However, changes in predicted microbiota metabolic function from meconium to transitional stool were only observed in vaginally-delivered neonates. Within sample comparisons showed that delivery mode was significantly associated with bacterial structure, composition and predicted microbiota metabolic function in transitional-stool samples, but not in meconium samples. Specifically, compared to vaginally delivered neonates, the transitional stool of C-section delivered neonates had lower proportions of the genera , and . These differences led to C-section neonates having lower predicted abundance of microbial genes related to metabolism of amino and nucleotide sugars, and higher abundance of genes related to fatty-acid metabolism, amino-acid degradation and xenobiotics biodegradation. In summary, microbiota diversity was reduced in the transition from meconium to stool, and the association of delivery mode with microbiota structure, composition and predicted metabolic function was not observed until the passing of the transitional stool after meconium.
剖宫产（C 型剖宫产）分娩最近被证明会导致小鼠体重过度增加，由于缺乏微生物从母亲到新生儿的自然传递，这种分娩方式会扰乱人类新生儿肠道微生物群的发育。新生儿在出生后数小时首先排出子宫内的肠道内容物（称为胎粪），随后在出生后 2 至 3 天排出反映宫外暴露的肠道内容物（称为过渡粪便）。剖宫产对新生儿肠道微生物群的影响何时出现尚不清楚。我们在巴西一家私立医院检查了 59 名新生儿[13 名通过择期剖宫产出生，46 名通过阴道分娩出生]仔细收集的胎粪以及随后的过渡粪便中的细菌 DNA。提取细菌 DNA，并使用 Illumina MiSeq（美国加利福尼亚州圣地亚哥）平台对 16S 基因的 V4 区域进行测序。我们在研究中的大多数胎粪样本中发现了细菌 DNA 的证据。胎粪的细菌 DNA 结构（即β多样性）与过渡粪便微生物群的结构有显著差异。从胎粪到粪便的转变过程中，细菌α多样性（例如观察到的细菌种类数量）显著降低，细菌组成发生变化（例如变形菌减少）。然而，仅在阴道分娩的新生儿中观察到从胎粪到过渡粪便的预测微生物群代谢功能的变化。样本内比较表明，分娩方式与过渡粪便样本中的细菌结构、组成和预测的微生物群代谢功能显著相关，但与胎粪样本无关。具体而言，与阴道分娩的新生儿相比，剖宫产分娩的新生儿的过渡粪便中，[具体属名缺失]属的比例较低。这些差异导致剖宫产新生儿中与氨基和核苷酸糖代谢相关的微生物基因预测丰度较低，而与脂肪酸代谢、氨基酸降解和外源性生物降解相关的基因丰度较高。总之，从胎粪到粪便的转变过程中微生物群多样性降低，并且直到胎粪后的过渡粪便排出后才观察到分娩方式与微生物群结构、组成和预测代谢功能之间的关联。
