Abstract: ObjectiveTo investigate the effects of antibiotics on the development of intestinal microflora in preterm neonates by 16S ribosome DNA(16S rDNA) high throughput sequencing technology.MethodsTotally 60 preterm neonates with gestational age of 30-36⁺⁶ weeks hospitalized in the intensive care unit of Hunan Maternal and Child Health Hospital from August 2019 to February 2020 were enrolled. According to the clinical treatment needs, preterm neonates were divided into two groups: feces of 35 patients in the antibiotic exposure group(antibiotics utilization ≥7 d) and 25 patients in the antibiotic non-exposure group(no use of antibiotics during hospitalization) were collected within 2 hours and 14 days after birth, respectively. Fecal flora was analyzed by 16S rDNA sequencing technology. Operational taxonomic units(OTU) were used to process the original data to obtain the final effective data, and all the effective data sequences of whole samples were clustered to form OTU. Venn diagram was used to identify the core microorganisms in different environments in combination with the species represented by OTU.ResultsThere were a large amount of intestinal bacteria in both groups within 2 h after birth, mainly including bacillus perfringens, streptococcus and staphylococcus, and the difference was not statistically significant(P> 0. 05). The top 3 intestinal flora were all perfringens, streptococcus and enterococcus within 2 h after birth and at 14th day of birth in the antibiotic exposure group(P> 0. 05). But pseudomonas saccharophil decreased significantly and escherichia coli increased significantly at 14th day of birth(P< 0. 05). The top 3 intestinal microflora were all bacillus perfringens, staphylococcus and enterococcus within 2 h after birth and at 14th day of birth in antibiotic non-exposure group(P> 0. 05). According to the Venn diagram of OTU distribution, the biodiversity within 2 h after birth was more than that at 14th day of birth in antibiotic exposure group; but at 14th day of birth, the biodiversity of the antibiotic non-exposed group was higher than that of the antibiotic exposed group.ConclusionThere are a large amount of intestinal flora in premature infants at birth. Antibiotics can significantly reduce the abundance of intestinal flora, leading to the development of more escherichia coli. Lactobacillus are not found in both groups at day 14 of birth. It is suggested to reduce the period of antibiotics utilization.