702 - Comparison of gut microbiota of small-for-gestational-age, appropriate-for-gestational-age, and large-for-gestational-age infants in late preterm and full-term infants.

Publication Number: 702.4489

Jae Kyoon Hwang, Hanyang University Medical Center, Seoul, Seoul-t'ukpyolsi, Republic of Korea; Sung Min Lim, Hanyang University Hospital, Seongdong-gu, Seoul-t'ukpyolsi, Republic of Korea; Seung Hyun Kim, Samsung Medical Center, Seoul, Seoul-t'ukpyolsi, Republic of Korea; Min‑Jin Kwak, university of florida, gainesville, FL, United States; G. Mustafa, Hanyang University, Seoul, Seoul-t'ukpyolsi, Republic of Korea; Rahul Sadashiv Tanpure, hanyang university, Seoul, Seoul-t'ukpyolsi, Republic of Korea; Byong-Hun Jeon, Hanyang University, Seoul, Seoul-t'ukpyolsi, Republic of Korea; Hyun-Kyung Park, Hanyang University College of Medicine, Seoul, Korea, Seoul, Seoul-t'ukpyolsi, Republic of Korea

Background: The gastrointestinal tract hosts a complex and diverse microbial community influenced by various factors such as gestational age, delivery method, feeding practices, antibiotics, probiotics, and environmental conditions. The neonatal gut microbiome, established shortly after birth, is crucial for both acute health and long-term neurodevelopment. It plays a vital role in nutrient absorption, energy storage, and metabolic regulation. Disruptions in this microbial community can impair nutrient absorption, hinder growth and neurodevelopment, and contribute to metabolic diseases.

Objective: This study aims to investigate the differences in gut microbiota composition among SGA, AGA, and LGA infants born after 35 weeks of gestation and at full term.

Design/Methods: The study included both preterm infants born at or after 35 weeks of gestation and full-term neonates. 43 neonates were enrolled in a neonatal intensive care unit/nursery room and divided into three groups based on weight for gestational age. Samples were grouped according to the date of collection. Genomic DNA was extracted from the fecal samples and underwent high-throughput 16S rRNA amplicon sequencing using Oxford Nanopore Technology.

Results: Proteobacteria increased and Firmicutes decreased in the SGA and LGA group than AGA group.
SGA infants have a microbiome dominated by Enterococcus faecium and Staphylococcus epidermidis, with minimal diversity. When analyzed by dividing the samples according to the use of antibiotics within 7 days, E. faecium was found in high concentrations in SGA.
AGA infants have a more balanced microbial community, with E. faecium still dominant but with significant contributions from other species like Enterococcus faecalis, and Lactobacillus rhamnosus.
LGA infants have a more diverse microbiome, with higher levels of gram-negative bacteria like Escherichia coli and Klebsiella pneumoniae, which could indicate a different immune response or result of antibiotics.

Conclusion(s): This study is the first to compare the gut microbiome communities of late preterm and full-term SGA, AGA, and LGA infants using nanopore sequencing. Enterococcus faecium emerged as a potential key player in the gut microbiota of SGA newborns regardless of antibiotic use.
Further research is necessary to address the study's limitations, including expanding on alpha and beta diversity analyses, utilizing PICRUSt for predicting metagenomic functional content, and incorporating metabolomics. Additionally, longer-term follow-up studies are needed to examine the relationship between gut microbiota and infant growth and development, such as catch-up growth.

Study design & Patient characteristics
Enrolled: Term & late preterm infant (over 35 weeks of GA)
SGA (weight < 10), AGA (40 < weight < 60), LGA (weight > 90) (percentile)

Taxonomic classification
Genus level shows Proteobacteria increased and Firmicutes decreased in the SGA and LGA group than AGA group.
Species level shows SGA infants have a microbiome dominated by Enterococcus faecium and Staphylococcus epidermidis, with minimal diversity.

Species level, within 7days, by antibiotics use.
Dividing the samples according to the use of antibiotics within 7 days, Enterococcus faecium was found in high concentrations in SGA.