A systematic review of the factors influencing microbial colonization of the preterm infant gut

Abstract

Prematurity coupled with the necessary clinical management of preterm (PT) infants introduces multiple factors that can interfere with microbial colonization. This study aimed to review the perinatal, physiological, pharmacological, dietary, and environmental factors associated with gut microbiota of PT infants. A total of 587 articles were retrieved from a search of multiple databases. Sixty studies were included in the review after removing duplicates and articles that did not meet the inclusion criteria. Review of this literature revealed that evidence converged on the effect of postnatal age, mode of delivery, use of antibiotics, and consumption of human milk in the composition of gut microbiota of PT infants. Less evidence was found for associations with race, sex, use of different fortifiers, macronutrients, and other medications. Future studies with rich metadata are needed to further explore the impact of the PT exposome on the development of the microbiota in this high-risk population.

Bacteroidota and Lachnospiraceae Integration Into the Gut Microbiome at Key Time Points in Early Life are Critical for Neurodevelopment

“…These results have together indicated that habitat ltering, i.e., variables that shape the intestinal environment, is a dominant driver of infant microbiome succession. Other studies have additionally shown that delivery mode shapes the initial colonizers of the infant gastrointestinal tract [62,76], which includes faecal microbes for vaginally delivered infants, such as Bacteroidota [78,79] complementing our study, and skin microbes for Caesarean-section infants. However, infants delivered at term possess an advantage as they can access the home environment usually relatively quickly, whereas preterm infants usually remain in the hospital environment at length with sanitation protocols preventing normal microbial dissemination [80].…”

“…Diet and antibiotics are known to have a large impact on the infant microbiome, exceeding stochasticity [33,62,76]. Further, a seminal study by Feng and colleagues has demonstrated that the in uence of relative microbial tness on infant microbiome succession appears to supersede historical contingency, i.e., the order of introduction of microbes [77].…”

“…This difference allows the effect of dispersal limitation on infant microbiome succession to be more closely examined in preterm infants, and a major nding of this study is that its in uence exceeds habitat ltering. That could explain why studies on enteral feeding [23,76] and antibiotics [76,81,82] for their health bene ts and effects on microbiome composition have yielded somewhat inconsistent results for preterm infants, despite their known effects on the term infant microbiome.…”

“…Further, the maternal microbiome can also exhibit dysbiosis, as the faecal and vaginal microbiome composition of mothers that deliver preterm has exhibited signi cant differences compared to mothers that deliver at term in other studies [86,87]. The effects of delivery mode on preterm infant health outcomes and microbiome succession can thus also be masked depending on a given study's cohort distribution [76]. Therefore, it is recommend that clinical variables should be considered sequentially for infant microbiome studies, rst by dispersal limitation factors (e.g., delivery mode, environment such as hospital versus home or urban versus rural, probiotics) then by habitat ltering factors (e.g., diet, prebiotics, antibiotics).…”

Postnatal age is strongly correlated with the early development of the gut microbiome in preterm infants

“…However, at 1 week of age, the gut microbiota of neonates delivered by cesarean section is characterized by high levels of Clostridium, but not Bifidobacterium and Bacteroides, compared with that of infants delivered by spontaneous vaginal delivery (13,16). Meanwhile, antimicrobial agents often reduce gut bacterial diversity and disrupt the ecological balance of the neonatal microbiome (12,(17)(18)(19).…”