Development of the Neonatal Intestinal Microbiome and Its Association With Necrotizing Enterocolitis

Abstract

Because of the complexity of these interactions, it is vital that we continue to investigate the host-bacterial axis in the developing intestine in both humans and in animal models.

Necrotizing enterocolitis in a full term infant

“…This leads to an alteration in the proportion of the commensal bacteria and increases the risk of NEC by promoting colonization with more resistant pathogens. To date no single causative bacterial agent has been identified; however, a generalized microbial imbalance of the intestinal flora with Firmicutes and Proteobacteria dominant dysbiotic patterns has been detected before the development of early or late onset NEC respectively [8,9]. Even though in most cases of NEC no specific microorganism can be considered causative (all cultures were negative in the case of our patient), viruses and bacteria have been consistently implicated somewhere along the pathogenic process.…”

“…Consequently, the infant's microbiota could have been significantly altered by his mother's course of antibiotics. Recent studies suggest the presence of a microbiome within the placenta and meconium, implying that the colonization process begins antenatally and before breastfeeding [8,9], contrary to the previous belief that the in-utero environment was sterile, and that the fetus was first colonized with bacteria at the time of birth. It is now known that there is a direct transfer of maternal intestinal bacteria to the fetus via dendritic cells or other immune cells, maternal mammary glands, breast milk and placental tissue [9].…”

“…It is well known that breast milk plays a direct role in imprinting the neonatal biome by adding certain bacterial species such as Staphylococcus, Streptococcus, Bifidobacterium and Lactobacillus to the infant's gastrointestinal tract (enteromammary pathway) [8]. Formulafed babies have a different microbial status than those fed human milk [9]. Additionally, breast milk contains immunoglobulins, growth factors, hormones, lactoferrin, glutamine, polyunsaturated fatty acids and oligosaccharides, which give beneficial microbes a specific substrate for growth.…”

Human milk oligosaccharide composition predicts risk of necrotising enterocolitis in preterm infants

“…Although HMO have profound effects on infant microbiota composition,18–20 the importance of microbiota composition on NEC onset and development is poorly understood 21–26. Whether microbial dysbiosis is a causative event or merely a marker of intestinal disease remains unknown 27. Instead, HMO may have direct effects on infant intestinal epithelial or immune cells, which might directly attenuate NEC risk, and also indirectly alter microbiota composition.…”

Calprotectin levels in necrotizing enterocolitis: a systematic review of the literature

“…However, to date no specific markers to screen for the disease have been identified. The association of FC with intestinal inflammatory diseases has been thoroughly investigated during the last decade [30]. It is believed that the presence of calprotectin in stool indicates increased neutrophil migration towards the intestinal mucosa, which is triggered by bowel inflammation [31].…”