Effect Of Initial Prolonged Empirical Antibiotic Therapy On The Development Of Intestinal Microbiota Of Preterm Infants

Part ?: the Effect of Antibiotic on the Intestinal Flora Diversity of Preterm Neonates During the First Week of Life by using PCR-DGGE?Objective? To analyze the effect of prolonged empirical antibiotic therapy on the intestinal microbiota community diversity of preterm infants and its dynamic change by 16 S rDNA PCR-denaturing gradient gel electrophoresis(DGGE).?Method? In the period of January 2014 to June 2015,thirty-six hospitalized preterm infants in Children's Hospital of Chongqing Medical University were enrolled and divided into three groups: One group is the piperacillin-tazobactam(PT)treatment group,one is the combination of Penicillin and Moxalactam(PM)treatment group,the another group is the antibiotic free(AF)group,the infants of the three groups were matched with each other by gestational age(+/-one week),delivery mode and birth weight.The meconium and fecal samples at d3,d5 and d7 were collected during the first week of life.After DNA extraction and PCR amplification,the microbial community diversity was analyzed through DGGE fingerprints.?Result? A total of 144 fecal samples were analyzed.However,the amplification of bacterial DNA from 36 meconium(< 12 h)failed and DGGE analysis was not performed.(1)The Shannon index of AF group on d3,5 and 7 was 1.39(0.94-1.94)?2.24(2.07-2.49)and 2.38(2.07-2.61);that of PT group at the same time point was 1.64(1.16-1.92)? 1.97(1.69-2.20)and 1.22(0.69-2.1)and that of PM group was 0.68(0-1.78)?1.78(1.47-1.94)and 1.69(1.53-2.09),respectively.On d3 of postnatal life,the infants of three groups did not differ in the diversity index of fecal bacterial community;on d5,the Shannon index of PM group was significantly lower than that of the AF group(p<0.05)and on d7,the Shannon index of both antibiotic therapy group was significantly lower than that of the AF group(p<0.05).(2)The Shannon index at all the 3 time points has no differences between the PM and the PT group(p>0.05).(3)The result of DGGE at all the 3 time points showed that the Shannon index of AF group gradually increased during the first week of life,while the Shannon index of PT group had a tendency of decrease.? Conclusion ? The antibiotic therapy can reduce the intestinal microbiota community diversity and different antibiotics can lead to the different result at the same time points.However,less than 3 days of antibiotic therapy has little effect on intestinal flora diversity.Part?: the Effect of Antibiotic on the Intestinal Microbiota Structure of Preterm infants by using High-throughput Sequencing? Objective ? To investigate the effect of prolonged empirical antibiotic therapy on the intestinal flora structure of preterm infants by using high-throughput sequencing.?Method? The fecal samples on d3 and d7 of all enrolled infants were studied by high-throughput sequencing and then the results were analyzed by bioinformatics methods.?Result? A total of 72 fecal bacterial DNA samples were analyzed.However,the amplification of bacterial DNA from one sample failed and high-throughput sequencing analysis was not performed.(1)The Shannon index did not differ among the three groups on d3 and d7,while the Shannon index of PT group and PM group significantly decreased on d7 as compared to that on d3,respectively(p<0.05).(2)The gut microflora structure was simple and the Firmicutes and Proteobacteria were dominant.(3)On d3,the microbiota structure was similar among the three groups;on d7,as compared with AF group,two(Pseudomonas and Streptococcus)were enriched on PT and PM group,while the other four(Citrobacter,Klebsiella,Veillonella and Clostridium)were decreased significantly(p<0.05).Enterococcus also increased significantly in PT group(p<0.05).In addition,the Bacillus was more prevalent in the PM group(p<0.05).?conclusion?The prolonged empirical antibiotic therapy can change the gut microflora structure and lead to the excessive growth of pathogenic bacteria and drug resistant bacteria like Enterococcus sp.and Streptococcus sp.Different antibiotics have different effects on the microbiota structure and less than 3 days of antibiotic therapy has little effect on intestinal flora structure.