Determinants of the Very Low-Birth-Weight Infant's Intestinal Microbiome: A Systematic Review.

The intestinal microbiome is the genetic material from microorganisms residing in the intestinal tract. Very low-birth-weight infants (VLBW; birth weight ≤1500 g) are a physiologically compromised population undergoing a unique period of initial intestinal microbiome establishment. Evidence supports a connection between the intestinal microbiome and gastrointestinal illness that disproportionately affects VLBW infants. Necrotizing enterocolitis, an inflammatory and often necrotic condition of the intestine, and late-onset sepsis, a bloodstream infection occurring after 3 days of life, are thought to be associated with delayed or abnormal intestinal microbiome development. Here, we review the determinants, or factors, that influence the VLBW infant's intestinal microbiome and discuss clinical implications. PubMed, Web of Science, EMBASE, and CINAHL were systematically searched for publications addressing factors with the potential to affect the intestinal microbiome of VLBW infants. Results indicate that infant's age and weight, mode of delivery, antibiotic exposure, medication use, feeding regime, environment, and perinatal-/infant-associated factors may be important determinants of the microbiome in this vulnerable population. Clinicians have opportunities to support positive development of the VLBW infant's intestinal microbiome through antibiotic stewardship, support of human milk feeding, and hygienic care practices.