P0767 - The Developing Microbiome in Preterm Multiplets vs Singletons- A Prospective Two-center Observational Study

Purpose:
The gut microbiome is the totality of microorganisms present in the gastrointestinal tract. Gut microbial development in preterm infants is affected by environmental and genetic factors; however, the extent to which these factors play a role in shaping the preterm infant gut microbiome is poorly understood. Studying the gut microbiome of multiplets (twins and triplets) in relation to their environmental exposures, such as enteral feeding type, can provide insight into genetic versus environmental influences on the gut microbiome. We aimed to investigate the gut microbiome of multiplets compared to singletons in relation to their nutritional intake. We hypothesized that genetically related preterm infants share more commonality in their gut microbiomes than non-related infants independent of different environments.

Methods:
We conducted a prospective, two-center, observational study. 50 sets of multiplets and 67 singleton controls, matched for birth gestational age, weight, sex, and mode of delivery, were recruited from the Neonatal Intensive Care Units (NICUs) of Tampa General Hospital (TGH) and Carle Foundation Hospital in Illinois. Two stool samples, between day of life (DOL) 4-18 and DOL 18-53, from each infant were analyzed for stool microbiome using 16S rRNA amplicon sequencing on Illumina Miseq. Multiplet and singleton stool samples were matched by postnatal age. Proportions of feeding type from the week prior to each stool sample were recorded. Microbiome composition and diversities were calculated using QIIME2 and statistical testing was performed in R. Alpha diversity, defined as variance within a sample, and beta diversity, defined as variance between samples, were analyzed.


Results:
Microbial beta diversity distances between genetically related infants were lower than genetically unrelated infants at different time points from two different geographically located NICUs (Figure 1). Genetic relatedness was the most important predictor of alpha diversity when compared to other factors such as weight, corrected gestational age, and type of milk consumed. The percentage of formula consumed positively correlated with Clostridioides and negatively correlated with Staphylococcus in the Carle singletons, but not in the Carle multiplets. On the other hand, the percentage of formula consumed positively correlated with Clostridioides in the TGH multiplets, but not in the TGH singletons (Figure 2).


Conclusion:
Our results show that preterm multiplet infants consistently shared more similarities in their gut microbiomes than unrelated individuals and that the differences in the gut microbiome between multiplets and singletons were not consistent in relation to their enteral feeding type. This indicates that genetics play a role in influencing the gut microbiome.