Establishment of the intestinal microflora in neonates

The intestinal microbiota is a complex ecosystem harbouring about 1014 micro-organisms composed of nearly 400 hundred species. If plays various important functions in the gut, including metabolic, flora, barrier and stimulation of the intestinal immune system. Most studies have been based on culture, but more recent molecular biology techniques have provided complementary information. The formation of this ecosystem begins rapidly in the newbom; it is sterile at birth and is based on contact with the matemal flora and the surrounding environment. Although little is known about the factors leading to the development of bacteria, numerous extemal factors will affect the microbial succession: made of delivery, environmental conditions, type of feeding, gestational age, and antibiotics. Recent data report a delay in intestinal colonization especially of enteric matemal bacteria. Which may be clue to strict hygiene measures during birth. The clinical impact of these variations is not known but they could lead to lock of barrier flora or poor immune system stimulation in the gut. Modulation of gut microbioto in neonates with infant formulas containing either probiotics, prebiotics or non viable bacterias and their metabolites, or nucleotides is discussed.