Influences Of Antibiotics And Probiotics On Intestinal Fiora In Late Preterm Infants

Objective The aim of this study was to investigate the establishment of the intestinal flora in late preterm infants and to explore the influences of antibiotics and probiotics by high-throughput sequencing.Methods According to the aim of this experiment and the clinic situation,we set a criteria of inclusion and exclusion for subjects who exposured to antibiotics.A total of 10 late preterm infants whose mothers and infants accepted antibiotics were included from NICU of the First Affiliated Hospital of Guangxi Medical University,and then were divided into two groups including antibiotic group and probiotic group.Antibiotic group were defined as infants whose mothers accepted antibiotics in the last week of pregnance and infants accepted antibiotics within 48 hs after birth(both duration ? 7 days).The probiotic group accepted the treatment of probiotics from day 3 to day 10 in addition to the administration of antibiotics as in the antibiotic group.Control infants with similar gestational ages,birthweight were selected from the population.Stool samples from each infant were collected at 3,7,and 14 days of age.DNA was extracted from stool samples using the QiAamp Fast DNAStool Mini Kit(Qiagen,Germany).The fecal bacterial composition and diversity were analysed by sequencing V3-V4 region of 16 S rRNA with Illumina Miseq platform.Results (1)16 S rDNA sequence data were generated from a total of 15 preterm infants with 44 samples.The data yielded sequences belonging 15 phyla,28 classes,62 orders,103 families,210 genera,289 species and 345 OTUs.The rarefaction curves and Shannon curves showed a reasonable sequenced data,and a near-complete sampling of the community.(2) In the control group,intestinal flora diversity increased gradually during the first 14 days of life.On the other hand,in the antibiotic group and probiotic group,the diversity index decreased from days 3 to 7,and then increased gradually in the next week.The diversity index on days 7 were significantly lower in the antibiotic group than in the control group and probiotic group(P<0.05).(3) In control group,Proteobacteria dominated the intestinal flora at 3 days of age,followed by Firmicutes,Bacteroidetes,Actinobacteria.Infants in the control group had slight decreases in abundance of Proteobacteria,and increases in Firmicutes,Bacteroidetes and Actinobacteria.At 14 days of age Firmicutes had become the clearly dominant population in control group,followed by Actinobacteria,Proteobacteria and Bacteroidetes.At genus levels,the intestinal flora in control group on days 3 was dominanted by facultative anaerobes including Escherichia-Shigella and Enterobacter.The facultative anaerobes such as Escherichia-Shigella and Enterobacter decreased gradually in control group,while the anaerobes including Bifidobacterium and Clostridium had a tendency of increase and dominated the intestinal flora at 14 days of age.However,there was a trend toward increased abundance of facultative anaerobes such as Streptococcus,Enterococcus,and so on.Furthermore,these facultativeanaerobes still had a considerable proportion in control group at 14 days of age.On the contrary,infants in the antibiotic group had slight increases in abundance of Proteobacteria(Escherichia-Shigella),and decreases in Firmicutes(Enterococcus and Streptococcus)and Actinobacteria(Bifidobacterium).Furthermore,the abundance of several phylum(i.e.Bacteroidetes,Planctomycetes,Deinococcus-Thermus and Cyanobacteria)was also significantly decreased and could not be detected after antibiotic exposure(P<0.05).There was no difference in the composition of intestinal flora at days 3between antibiotic group and probiotic group.With chronological progression,there was a trend toward increased abundance of Actinobacteria(Bifidobacterium)during the first 14 days of life.At 7 days of age,the abundance of Actinobacteria(Bifidobacterium)in probiotic group was significantly higher than infants in antibiotic goup(P<0.05).Conclusion 1.The characteristics of colonization and development of intestinal flora in late preterm infants: An early dominance of Proteobacteria(facultative anaerobes such as Escherichia-Shigella and Enterobacter were the most abundant genera)changes to a dominance of Firmicutes,followed by Actinobacteria,Proteobacteria and Bacteroidetes.For samples from week 2 of life,strictly anaerobic bacteria such as Bifidobacterium and Clostridium were the predominant genera.2.Antibiotics exposure can significantly reduce the diversity of intestinal flora in the late preterm infants and affect bacterial colonization.As a result,the relative abundunce of beneficial bacteria(including Bifidobacterium)decreased,but that of potentially pathogenic bacteria(including Escherichia-Shigella and Enterobacter)increased.3.Probiotic supplement can increase the diversity of intestinal flora and strengthen the colonization of Actinobacteria(mainly bifidobacterium).Probiotic mayminimize antibiotic-induced disruption of gut microbiota,thus promoting the recovery of intestinal microbiota.