"Your earliest gut microbes probably have lifelong consequences, but we know very little about how these microbial communities assemble," said senior author Phillip I. Tarr, MD, the Melvin E. Carnahan Professor of Pediatrics. "Do these populations form as a result of random encounters, with an infant's gut supporting the growth of bacteria that enter this organ by chance? Or does the host have a role in selecting the microbes? Our research indicates that the gut is destined to define the bacteria that inhabit it. At 33-36 weeks after conception, preterm infants have very similar microbial populations in their guts."
The research appears Aug. 11 in the Proceedings of the National Academy of Sciences
) online early edition.
Bacterial colonization has lasting effects — influencing health and development, immune function, resistance to infection, and predisposition to inflammatory and metabolic disorders — yet, until now, little has been known about how the microbes get there.
Collaborators at The Genome Institute at Washington University School of Medicine used DNA sequencing to tally the bacterial populations in 922 stool samples from 58 premature infants. The babies, patients in the neonatal intensive care unit (NICU) at St. Louis Children's Hospital, ranged from 23-33 weeks in gestational age and weighed 1,500 grams (3 pounds, 5 ounces) or less.