The Analysis Of Factors Affecting The Initial Colonization And Dynamics Of The Infant Gut Microbiota

Objective: To investigate the factors influencing on the initial colonization and dynamics of the infant gut microbiota by high-throughput sequencing,providing a theoretical basis for the establishment of infant intestinal microecology balance by early intervention with probiotics.Methods: 106 infants who met the entry criteria were recruited during the period of October 2016 to January 2018,all of them were born in the The Third Hospital of Hebei Medical University or The Fourth Hospital of Shijiazhuang City.Stool specimens were collected at 1st day,3rd day,7th day and 1st month,3rd month,6th month after birth and the feeding type,drug usage were followed-up at the same time.After extracting the DNA of stool samples,the sequences of regions V4 of bacterial 16 S rRNA gene were generated with high-throughput sequencing on HiSeq2500 PE250 sequencing platform.Data was analysed with Mothur software.Results: 1 The information of specimens106 infants were enrolled,57 of them were vaginal delivered,and the others were delivered by cesarean section.Stool specimens were collected at 1st day,3rd day,7th day and 1st month,3rd month,6th month after birth.636 specimen samples should be collected,whereas 89 of them weren't available due to the illness or medicine taken of the infants during the time,at a rate of 14.00%,547 samples gathered at length.DNA couldn't be extracted from 42 samples,and amplification failure occurred in 54 samples.As a result,451 specimen samples were sequenced.2 The influence of delivery mode on meconium microbiota 2.1 There was no significant difference in the diversity of meconium microbiota between the cesarean infants and vaginally infants.2.2 The meconium microbiota of the vaginal-birth infants is dominated by members of the Bacteroidetes and Actinobacteria phyla,while the cesarean-delivered infants are Firmicutes.Various Bacteroides,Prevotella,Enterococcus are significantly more abundant in vaginally infants,however,Microbacterium,Arthrobacter,Propionibacterium,Bacillus,Salmonella are more abundant in cesarean infants.3 The impacts of delivery mode and feeding type on the infant gut microbiota diversity 3.1 Compared with the infants delivered via cesarean section,the vaginally delivered infants demonstrate increased diversity of gut microbiota on the whole.3.2 Feeding pattern does not have much effects on the gut microbiota diversity in vaginally delivered infants.3.3 For the infants born by cesarean section,the infants fed with exclusive formula with probiotic exhibit higher diversity than the breastfeeding and mixed feeding ones.3.4 The gut microbiota of the cesarean infants fed with formula containing probiotic become more diverse with age,while the breastfeeding and mixed feeding infants do not change much.4 The age-related changes of Top 10 bacterial species of the infant gut with different delivery mode and feeding type.4.1 Overall,Lactobacillus and Bifidobacterium increase gradually along with the reduce of Lactococcus,Bacillus and Acinetobacter over time.4.2 Bacillus and Peptoclostridium seem to be more frequent in cesarean section delivered infants compared with vaginally delivered infants,but Bacteroides genus is opposite.After feeding babies with probiotic formula,the relative abundance of the Bacillus,Peptoclostridium genus decreases,however,the change of Bacteroides genus is not obvious.4.3 For the infants fed with formula containing probiotic,Enterobacter and Streptomyces are substantially higher,while the Lactococcus and Pseudomonas are lower than the other groups.5 The variations of discrepancy between different groups with age.5.1 The variations between different delivery mode disappear gradually as the years go by.5.2 The variations between different feeding type diminish little by little as babies age.5.3 The difference increases at 6th month after birth of the infants with different delivery mode or feeding type.Conclusions:1.Both the delivery mode and feeding type have a major impact on the initial colonization and dynamics of the infant gut microbiota.2.Bacteria can be detected in the neonatal meconium,delivery mode is a crucial influencing factor.3.The vaginally delivered infants demonstrate increased diversity of gut microbiota compared with the infants delivered via cesarean section,which lasts till 6th month after birth of the infants,and the variations diminish with age.4.The variations between different feeding type diminish little by little as babies age.5.Early intervention of probiotics could optimize and modify the gut microbiota,which can promote the composition of formula fed infant intestinal flora similar to the breastfeeding ones and help establishing a stable pattern of ecology as soon as possible.