Data from: Trends and determinants of gastric bacterial colonization of preterm neonates in a NICU setting

Background: Newborn gastrointestinal (GI) tract is considered sterile but rapidly acquires a diverse microbiota from its intimate environment. Early acquisition of a bacterial species in the upper GI tract may play a role in establishing the colonic microbiota. There is paucity of molecular data on the upper GI tract microbiota in preterm neonates. Methods: Gastric aspirates from 22 neonates with an average gestational age 27.7 weeks (±2.8), weighing 973.2 grams (±297.9) admitted to a neonatal intensive care unit were collected prospectively from weeks 1-4 of life. All samples were evaluated for microbiota using 16S rRNA-based Denaturing Gradient Gel Electrophoresis. Bacterial species colonization and its association with maternal and neonatal demographics, and neonatal clinical characteristics were analyzed. Results: Bacteroides spp. was the predominant species in all four weeks. Bifidobacterium spp. colonization was significantly higher in exclusively breast milk fed compared to partially breast milk (PBM) fed neonates in first (p = 0.03) and third (p = 0.03) week of life. Anaerobic bacteria colonization decreased from first through fourth week of life (p = 0.03). Aerobic bacteria colonization was highly dynamic throughout the four week period. Premature rupture of membrane (p = 0.05) and birth outside of study hospital (p = 0.006) influenced the acquisition of bacteria in the first week of life. Birth weight was positively correlated with total number of bacterial species (p = 0.002) and anaerobes (p = 0.004) in PBM-fed neonates during the fourth week of life. H. pylori and Ureaplasma were not detected in any of our samples. Conclusion: Gastric bacterial colonization in preterm neonates is unstable during early weeks of life. Delayed oral feeding and use of antibiotics may be responsible for paucity of bacterial species. Monitoring of the gastric microbiota and concurrent examination of stool microbiota may yield important information on the utility of gastric signature patterns for predicting colon microbiota that may drive GI and immune dysfunctions.研究背景：新生儿胃肠道（gastrointestinal, GI）曾被认为是无菌环境，但会快速从周边环境中获得多样化的微生物群。上胃肠道早期定植的细菌物种，可能在结肠微生物群的建立过程中发挥关键作用。目前针对早产儿上胃肠道微生物群的分子生物学数据仍较为匮乏。 研究方法：本研究前瞻性收集了22名入住新生儿重症监护病房（neonatal intensive care unit, NICU）的早产儿的胃液抽吸物。这些早产儿的平均胎龄为27.7周（±2.8），平均出生体重为973.2克（±297.9），样本采集时间覆盖出生后第1至第4周。所有样本均采用基于16S核糖体RNA（16S rRNA）的变性梯度凝胶电泳（Denaturing Gradient Gel Electrophoresis）进行微生物群分析。随后对细菌定植情况，及其与产妇、新生儿人口学特征及新生儿临床特征的相关性进行了统计分析。 研究结果：拟杆菌属（Bacteroides spp.）是出生后第1至第4周内的优势菌群。在出生后第1周（p=0.03）及第3周（p=0.03），完全母乳喂养的早产儿的双歧杆菌属（Bifidobacterium spp.）定植率显著高于部分母乳喂养（partially breast milk, PBM）的早产儿。厌氧菌定植率随出生后第1至第4周呈逐渐下降趋势（p=0.03）。需氧菌定植率在整个4周观察期内呈现高度动态变化。在出生后第1周，胎膜早破（premature rupture of membrane, p=0.05）及非本研究医院分娩（p=0.006）会影响细菌的早期定植。在出生后第4周的部分母乳喂养早产儿中，出生体重与细菌物种总数（p=0.002）及厌氧菌数量（p=0.004）呈正相关。本研究未在任何样本中检出幽门螺杆菌（Helicobacter pylori, H. pylori）及脲原体属（Ureaplasma）。 研究结论：早产儿早期数周内的胃内细菌定植状态并不稳定。延迟经口喂养及抗生素使用可能是导致细菌定植匮乏的主要原因。对胃微生物群进行监测，并同步开展粪便微生物群检测，或可为利用胃微生物特征谱预测结肠微生物群的应用价值提供重要参考——而结肠微生物群异常可能与胃肠道及免疫功能紊乱密切相关。