AUTHOR=Fu Xin , Li Siwen , Jiang Yanfang , Hu Xintong , Wu Hui 

TITLE=Necrotizing Enterocolitis and Intestinal Microbiota: The Timing of Disease and Combined Effects of Multiple Species

JOURNAL=Frontiers in Pediatrics

VOLUME=Volume 9 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/pediatrics/articles/10.3389/fped.2021.657349

DOI=10.3389/fped.2021.657349

ISSN=2296-2360

ABSTRACT=Abstract
Background
The purpose of this study was to investigate the relationship between the intestinal microbiota and necrotizing enterocolitis(NEC).
Methods
16S rRNA gene sequencing was used to compare the microbial composition of faeces. The first sample was collected within 48 hours after birth, then once per week until the NEC diagnosis and finally 1-2 weeks after treatment or 28 days after birth. 
Results
The alpha diversity of the microbiota in the NEC group was higher than that in control group. Beta diversity analysis showed the control group had a higher similarity at the onset of NEC, while the NEC group was distributed in subgroups. LEfSe and taxonomic composition analysis indicated the abundance of Bacteroides and Actinobacteria in NEC infants at birth was much higher than that in the control group, and this trend continued until NEC occurred. At this time, Rhizobiales, Dysgonomonas, Ochrobactrum, Ralstonia, Pelomonas, Acinetobacter, etc. also were more abundant in NEC infants. The upregulated differential metabolic pathways in the NEC group were mainly concentrated on degradation/utilization/assimilation, biosynthesis and generation of precursor metabolites and energy.
Conclusions
1. The microbial community differs according to the time of NEC diagnosis (bounded by 20 days). 
2. No single microorganism is related to NEC, and the combined effect of multiple species is of great significance in the occurrence of NEC. Premature infants are easily affected by bacteria living in the environment, and compared with ordinary premature infants, NEC infants have a higher abundance of water-borne bacteria, therefore, attention should be paid to the contamination of water sources and various ventilator pipelines for premature infants hospitalized in the NICU. 
3. In-depth study of the mode of microbial colonization in premature infants combined with the different functions of various metabolic pathways involved in different microorganisms may be able to identify the cause of NEC.