Effect Of Prenatal Antibiotic Exposure On Intestinal Microecology Of Preterm Infants

Objective:To investigate the effects of prenatal antibiotic exposure on the intestinal flora of preterm infants in the early postnatal period by high-throughput sequencing.To study the effects of prenatal antibiotic exposure on the intestinal flora of preterm infants by analyzing the characteristics of the composition and diversity of the intestinal flora,the abundance of bacterial species,and the biological functions of marker microorganisms and flora between the prenatal antibiotic-exposed and non-exposed groups.Methods:Preterm infants born between December 2021 and October 2022 and admitted to the Neonatal Intensive Care Unit of Dalian Women and Children Medical Center（Group）Sports New City Campus with a gestational age of 32^0/7-36^6/7were selected.Preterms were divided into antibiotic-exposed and non-exposed groups according to whether the mothers applied antibiotics prenatally.Maternal and preterm infant data were collected.Maternal data included age,mode of delivery,body mass index（BMI）,premature rupture of membranes≥18 hours,gestational hypertension,gestational diabetes mellitus,gestational combined thyroid disease,and prenatal glucocorticoid use;preterm infant data included gestational age,birth weight,gestational age sex,1 and 5-minute Apgar scores,respiratory distress syndrome（RDS）,neonatal pneumonia,days of postnatal antibiotics,neonatal sepsis,necrotizing enterocolitis（NEC）,and days of hospitalization.Stools were collected within 24 hours after birth and high-throughput sequencing was applied to further compare the differences between the two groups by OTU clustering,Alpha diversity,Beta diversity,species composition analysis,LEf Se differential analysis,and KEGG pathway annotation to predict biological function.Results:A total of 29 preterm infants were included in this study,15 in the antibiotic-exposed group and 14 in the non-exposed group.There were no statistical differences in maternal data between the two groups:age,BMI,mode of conception,mode of delivery,premature rupture of membranes≥18 hours,gestational hypertension,gestational diabetes,gestational combined thyroid disease,and prenatal glucocorticoid use（P>0.05）.There was no statistically significant difference between the two groups in terms of preterm infant data:gestational age,birth weight,sex,1 and 5 minute Apgar score,RDS,neonatal pneumonia,days of postnatal antibiotics,neonatal sepsis,NEC,and days of hospitalization（P>0.05）.Stools within 24 hours after birth were sequenced by high-throughput sequencing,yielding a total of 2289 OTUs,of which 1510 OTUs were unique to both groups,212 unique to the exposed group and 567 unique to the non-exposed group.Alpha diversity analysis between groups showed that the prenatal antibiotic Simpson index and Coverage index were smaller than the non-antibiotic exposed group,and the difference was not statistically significant（P>0.05）.By species diversity analysis,the abundance of cyanobacterial phylum was higher in the prenatal antibiotic exposed group than the non-exposed group at the phylum level,and the difference was statistically significant（P<0.05）,and the thick-walled phylum,anthropoid phylum,anthropoid phylum and actinomycetes dominated at the phylum level;the abundance of E.coli genus was higher in the exposed group than the non-exposed group as seen at the order,family,genus and species level,and the difference was statistically significant（P<0.05）.Comparison of the differences in flora between the two groups by LEf Se analysis revealed that Ralstonia spp.were more present in preterm infants in the non-exposed group,and Exiguobacteraceae,Exiguobacterium,Enterobacteriales,Enterobacteria spp.Escherichia,and Cyanobacteria were more present in the exposed group,and the difference was statistically significant（P<0.05）.annotation of the KEGG pathway suggested that the function of human disease causing intestinal flora was higher in the exposed group of preterm infants,which were higher than the non-exposed group in Shigellosis,bacterial infectious diseases,and in the function of amino acid biosynthesis.Preterm infants in the antibiotic-exposed group were lower than the non-exposed group,and the difference was statistically significant（P<0.05）.Research Conclusions:1.OTU analysis showed that the species distribution of intestinal flora was different between the antibiotic-exposed and non-exposed groups.2.The preterm infants in the prenatal antibiotic-exposed group showed a decrease in the abundance and diversity of intestinal flora in the early postnatal period compared to the non-exposed group,with elevated intestinal pathogenic bacteria（e.g.,E.coli,etc.）and decreased beneficial bacteria（e.g.,bifidobacteria,etc.）,which may lead to delayed colonization of the intestinal flora.3.In the comparison of flora functions,the intestinal flora of preterm infants in the exposed group had higher functions of causing human diseases,and they were higher in shigellosis and bacterial infectious diseases than in the non-exposed group,and in the function of amino acid biosynthesis,preterm infants in the antibiotic-exposed group were lower than in the non-exposed group.