Translated Abstract
Objectives:
The purpose of this article is to explore the structure of intestinal microbial flora and intestinal microbial diversity of diarrhea or healthy infants with 2 years old at different stage of the month, to explore influencing factors of intestinal microbial flora structure and diversity and to get some helpful advises for infant supplementary food add and more theoretical basis for infant diarrhea prevention and management.
Methods:
Cross-sectional study design was used, data were sampling according to the age stratification in diarrhea and healthy children respectively. One completed sample including one questionnaire and one corresponding stool sample of infant. The structure of infant intestinal microbial flora and diversity were carried out by Next Generation Sequence technology. Types of supplementary food were calculated by principle component analysis combined with clustering analysis; Quantitative data was analyzed by t test or variance analysis and qualitative data was analyzed by chi-square test; Covariance analysis were adopted to analyze the influencing factors of infant stool microbial flora structure and diversity after controlling the general social demography factors,diarrhea, month of age, feeding terms and supplementary terms in turn.
Results:
A total of 56 diarrhea infants and 59 healthy infants were enrolled for subsequent analysis; Of the 115 infants, 18 cases belong to newborn group, 24 cases belong to low age group (29 days~5.99 month), 39 cases belong to median age group (6 month~11.99 month), 34 cases belong to high age group (12 month~ 24month).The most abundant phylum of microbial communities were Proteobacteria (46.59% ± 11.41%), Firmicutes (17.32% ± 12.48%), Bacteroidetes (12.66% ± 8.37%), Acidobacteria (3.23% ± 4.32%).
Influence facts of the structure and diversity of infants intestinal microbial community:
Social demographic characteristic: social demographic characteristics were not significant factors in shaping infants feces microbial diversity. The relative abundance of Bacteroides was higher in Cesarean delivery infants（Z=-2.444, p=0.015）.
Feeding mode: infant fecal Firmicutes were much more abundant in “Artificial feeding” infants (F=3.688, p=0.014). Proteobacteria were much more abundant in “Breast feeding” infants (F=2.707, p=0.049). Diversity of Actinobacteria were much higher in “NLCFA”. Bifidobacteriaceae、Ruminococcacea were less abundance in “NLCFA”. Enteribacteriaceae we more abundance in “NLCFA”.
Age: The abundance of Firmicutes in four different age groups were significant different (F=3.139，p=0.028). The relative abundance of Proteobacteria and Bacteroides were significantly decreased as infants get older (F=2.988，p=0.034，F=6.524，p＜0.001).
Diaeehea or not: Healthy infants were significantly higher in relative abundance of phylum Firmicutes than diarrhea infants (F=4.177, p=0.043); Healthy infants were also significantly higher in relative abundance of phylum Proteobacteria (F=8.235, p=0.005)and phylum Actinobacteria (F=5.768, p=0.0018), also in the diversity of phylum Firmicutes (2.52±0.49 vs 2.29±0.63).
Factors affecting infant intestinal colonization resistance:
Social demographic characteristic: Infants born in urban were significantly associated with stronger colonization resistance. Higher maternal education level or mother working with their brains were significantly associated with stronger colonization resistance.
Diarrhea, Months, Feeding mode: It’s plausible that diarrhea infants were positively associated with stronger colonization resistance. Colonization resistance were positively associated with the age. Colonization resistance were higher in “ACFA” term.
Diversity in taxonomy level of phylum, family, genus were positively associated with B/E index and negatively associated with the relatively abundance of enterobacteriaceae and enterococcaceae significantly. The diversity of Actinobacteria and Bacteroidetes were positively associated with the relatively abundance of enterobacteriaceae and enterococcaceae and negatively associated with B/E index significantly. The relatively abundance of Firmicutes were positively associated with B/E index and negatively associated with the relatively abundance of enterobacteriaceae and enterococcaceae significantly.
Conclusions:
With the adding of complementary food, the diversity of intestinal microbial increased. Adding a rich variety of complementary food was suggested. The raising of colonization resistance were positively associated with the richness of intestinal microbial flora community, phylum Firmicutes played a important role in maintaining the stability of intestinal tract, while exceeded of phylum Actinobacteria and phylum Proteobacteria might lead the intestinal microbial community into a mess.
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