To Probiotic or not to probiotic: using metagenomics to compare the gut microbiome of infants who fulfill probiotic-treatment criteria with those who do not.

Preterm birth is associated with the development of both acute and chronic disease, potentially, through the disruption of normal gut microbiome development. Probiotic treatment may correct for these microbial imbalances and, in turn, mitigate disease. However, the criteria for probiotic treatment limits its usage to the most premature (< 32 weeks gestation) and small for gestational age infants (< 1,500 g). Here we used a combination of amplicon and shotgun metagenomic sequencing to compare the gut microbiome of preterm infants who fulfil the criteria for probiotic-treatment and those who do not. We aimed to determine if the stringent criteria for probiotic treatment is putting late-preterm infants at a disadvantage.