低出生体重儿肠道微生态构建影响因素的动态监测

目的 动态监测低出生体重儿肠道菌群，分析不同体重、不同喂养方式及疾病状态等因素对患儿肠道微生态的影响，为规范临床低出生体重儿宫外营养支持措施及治疗手段提供依据。方法 应用16S rRNA荧光定量PCR技术检测正常新生儿和低出生体重儿生后第1、3、7天粪便中大肠埃希菌、肠球菌、乳杆菌及双歧杆菌的含量。结果 （1）在生后7 d内，无论正常新生儿还是低出生体重儿，其粪便中大肠埃希菌、肠球菌、乳杆菌和双歧杆菌的含量均随日龄的增加而增加，且生后7 d内正常新生儿的粪便中大肠埃希菌、肠球菌、乳杆菌和双歧杆菌的含量均显著高于低出生体重儿（P<0.05），正常新生儿生后7 d内粪便中各细菌的增长率均高于低出生体重儿。（2）体重2 000~2 500 g的低出生体重儿粪便中大肠埃希菌和肠球菌在各日龄中的含量明显高于体重<2 000 g的新生儿（P<0.05）；同时其粪便中双歧杆菌和乳杆菌含量在3日龄和7日龄阶段明显高于体重<2 000 g的新生儿（P<0.05）。（3）3日龄和7日龄母乳喂养组的低出生体重儿粪便中双歧杆菌和乳杆菌含量明显高于乳制品喂养组（P<0.05）；且母乳喂养组新生儿生后7日内粪便中大肠埃希菌、乳杆菌和双歧杆菌含量的增长率均高于乳制品喂养组，尤其是双歧杆菌的增长率（126.49% vs 54.81%）。（4）合并并发症的3日龄和7日龄的低出生体重儿，粪便中乳杆菌和双歧杆菌含量均明显低于无合并症的低出生体重儿（P<0.05）；且无并发症组的低出生体重儿其粪便中肠球菌、乳杆菌和双歧杆菌的增长率均高于有并发症组的低出生体重儿，大肠埃希菌增长率则低于有并发症组。结论 低出生体重儿肠道菌群的定植时间晚且数量少，体重、喂养方式及有无并发症是影响新生儿肠道菌群丰度的重要因素。母乳喂养可促进低出生体重儿肠道中益生菌的定植。疾病因素会导致肠道菌群丰度的降低，使肠道菌群紊乱，其程度可能与病情的严重程度相关。

Dynamic monitoring on influencing factors ofgut microecology in low birth weight infants

Abstract: Objective To monitor the intestinal flora of low birth weight (LBW) infants dynamically and analyze the influencing factors of intestinal microflora, such as birth weight, feeding patterns and health condition, in order to provide experimental evidence for nutritional therapy of LBW infants. Methods 16S rRNA quantitative real-time PCR was used to detect the levels of E. coli, Enterococci, Lactobacilli and Bifidobacteria in the feces of normal newborns and LBW infants on the first, third and seventh day after birth. Results (1) The contents of E. coli, Enterococci, Lactobacilli and Bifidobacteria in the feces of normal newborns and LBW infants increased with the passage of time within 7 days after birth; the levels and growth rates of these bacteria were obviously higher in normal newborns than in LBW infants (P<0.05). (2) The contents of E. coli and Enterococci in feces of the infants weighing 2,000 to 2,500 grams were significantly higher than those weighing less than 2,000 grams within 7 days after birth (P<0.05), and the contents of Bifidobacteria and Lactobacilli were significantly higher on the 3rd and 7th day (P<0.05). (3) The contents of Bifidobacteria and Lactobacilli were significantly higher in breast-fed infants than in dairy-fed infants in LBW group on the 3rd and 7th day (P<0.05). The growth rate of E. coli, Lactobacilli and Bifidobacteria in the breast-fed infants were higher than in dairy-fed infants, especially that of Bifidobacteria (126.49% vs 54.81%). (4) LBW infants with complications had significantly lower levels of Lactobacilli and Bifidobacteria in feces than those without complications on the 3rd and 7th day (P<0.05). The growth rate of Enterococci, Lactobacilli and Bifidobacteria in the feces of LBW infants without complications were higher than those with complications, but the growth rate of E. coli was lower. Conclusion The colonization of intestinal microflora in LBW infants was delayed and deficient. Birth weight, feeding patterns and complications have a great influence on the intestinal flora of newborns. Breastfeeding promotes the colonization of probiotics in the gut of LBW infants. Diseases can lead to a decrease of intestinal flora and causes alteration of intestinal flora, and the extent of the alteration may be related to the severity of the disease.