Characteristics of the intestinal microbiota and metabolism in infants with extrauterine growth restriction

BACKGROUND: Infants with extrauterine growth restriction (EUGR) experience significant postnatal growth restriction in the first week after birth, which indicates a failure of energy absorption. This study aimed to determine the different intestinal microbial species and metabolites between infants with EUGR and those without EUGR. METHODS: A total of 73 infants hospitalized in a neonatal intensive care unit were enrolled and divided into the EUGR group (n=50) and the non-EUGR group (n=23). Fecal samples were collected during hospitalization. Bacterial species and their relative abundance were identified with metagenome sequencing. The metabolites in the feces and blood were identified with a liquid chromatography-mass spectrometry (LC-MS) based non-targeted metabolome. RESULTS: The intestinal microbiota of the EUGR group contained less Bacteroides vulgatus, Dorea unclassified, Lachnospiraceae bacterium 1_1_57FAA, and Roseburia unclassified compared to that of the non-EUGR group. More importantly, the intestinal microbiota of the EUGR group contained Streptococcus mitis_oralis_pneumoniae, while that of the non-EUGR group did not. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) prediction and a correlation analysis identified that the majority of different microbial species higher in the non-EUGR group were related to metabolism. The results of the non-targeted metabolome revealed that several metabolites in the feces and blood were much higher in either group, and some of which were related to the different microbial species. CONCLUSIONS: This study identified several different intestinal microbial species and metabolites in the patients’ feces and blood, which may provide evidence to identify the biomarkers of infants with EUGR.