Effects Of ?-lactam Antibiotics On The Colonization Of Gut Microbiota And Metabolites In Late Preterm Infants

Objective To explore the effects of ?-lactam antibiotics on the colonization of intestinal microbiota and their metabolites.Methods Sixteen hospitalized late preterm infants were enrolled and divided into ?-lactam antibiotic treatment(AT)group(duration<7d)and antibiotic free(AF)group.Fecal samples from each infant were collected at 3,7,and 14 days of age.Then after extracting all the bacterial DNA,the microbial community diversity and composition was analyzed through Illumina high-throughput sequencing technology,and liquid chromatography-mass spectrometry(LC-MS)platform was used to analyze the metabolites in the two groupsResults?The results show that Shannon index of AT group decrease from 3 to 7 days,but increased from 7 to 14 days,while the Shannon index ofAF group is relatively stable.The diversity of gut microbiota in AT group at 7d were significantly lower(P<0.05)when compared with the AF group.Comparing the Shannon index of bacteria on Day 3?Day 7 and Day 14,statistical differences were found in the AT group Day 7 and Day 14.?The microbial community analysis results showed that Proteobacteria,Firmicutes,Actinobacteria and Bacteroidetes were the most dominant in all samples.With the increasing of the age,the proportion of Proteobacteria in AF group gradually decreased,and the Firmicutes and Actinobacteria increased.However,the proportion of Bacteroidetes was first increased and then decrease.On the other side,the proportion of Proteobacteria in AT group had a special change of descend firstly then ascend,while the Firmicutes was opposite.Compared the proportion of bacteria on Day 3 with that on Day 7,we found the change in Firmicutes,Proteobacteria and Planctomycetes in AF group have statistical differences(both P<0.05).At genus level,the bacterial composition at the three time points from 16S rRNA gene sequencing show that Enterobacteriaceae unclassified was dominant in both groups,but Enterococcus had relatively high abundance in AT group.There were significantly differences in Bacteroides,Lactococcus,Reyranella,Gp6,Devosia and Brevundimonas(both P<0.05).Furthermore,we only found the Fusobacterium in AF group and Sutterella in AT group.In general,the abundance of Enterobacteriaceae unclassified gradually decreased,while the AT group was opposite.Moreover,the abundance of Bifidobacterium growth was fast in AF group.?According to the fecal metabolomic analysis,We found L-Lysine,L-Tyrosine,L-Serine,L-Threonine,Propionic acid,Hyocholic acid,Taurine,had statistically significant differences on Day 3 between the two groups(both P<0.05).,and Choline,Tyramine,L-Proline,L-Isoleucine,L-Lysine,L-Methionine,Taurocholic acid,Taurodeoxycholic acid,Tauro-b-muricholic acid,3a,7b,12a-Trihydroxyoxocholany 1-Glycine,Erythrose,had statistically significant differences on Day 7 between the two groups(both P<0.05),and L-Histidine,L-Acetylcarnitine,Hypoxanthine,Adenosine monophosphate,Malonic acid,Melibiose,Palmitelaidic acid,Trehalose,N-Acetylneuraminic acid had statistically significant differences on Day 14 between the two groups(both P<0.05).There were twenty-nine metabolic pathways had statistically significant differences on Day 3,Day 7 and Day 14(both P<0.05),including Propanoate metabolism,Arachidonic acid metabolism,Aminoacyl-tRNA biosynthesis,Biosynthesis of amino acids,Phenylalanine metabolism,Monobactam biosynthesis,ABC transporters,Glycine,serine and threonine metabolism,Pantothenate and CoA biosynthesis,Biosynthesis of antibiotics,Novobiocin biosynthesis,Carbapenem biosynthesis,Cyanoamino acid metabolism,Glyoxylate and dicarboxylate metabolism,C5-Branched dibasic acid metabolism,Histidine metabolism,Purine metabolism.The correlation analysis of fecal metabolites and bacterial compositions showed that several important amino acids show a positive correlation with most gut microbiota in Day 3,while it had negative correlation with few bacteria.It is noteworthy that the Bacteroidetes and Parabacteroides show a positive correlation with Propionic acid.At 7 days,the genus of Streptococcus and Clostridioides exhibited positive correlation with several important amino acids such as,L-Serine and L-Glutamate,and show a negative correlation with choline and Taurodeoxycholic acid.AT last,there was an obvious correlation fecal metabolites and genus of Clostridioides,and some metabolites such as Melibiose had positive correlation with bacterial except Enterococcus.Conclusion ? ?-lactam antibiotics treatment can significantly changes the bacterial diversity and composition,and caused the pathogenic bacteria increased,such as Enterococcus.Besides,it can also lead to the beneficial bacteria decreased.?And the change trends of metabolites and related metabolic pathways were similar with the results analyzed by high-throughput sequencing,Antibiotics can make the intestinal microbiota metabolism disturbed,and it mainly expresses that the changes of the amino acid,choline,short chain fatty acid and bile acid.Besides,several important metabolic pathways have also suffered,and it may be related to the reduce of the Bacteroides.In summary,application of antibiotics had a marked impact on the composition of gut microbiota as well as the metabolites and metabolic pathways.