Microbiome and early life

Abstract

Under physiological conditions, the fetus is protected from exposure to viable microorganisms. With rupture of membranes and passage through the birth canal, the neonate becomes exposed to bacteria that colonize maternal body surfaces and the environment. These bacteria start to establish the enteric microbiota initially characterized by low bacterial diversity and high interindividual variation. This makes the neonatal and early infant microbiota particularly vulnerable to exogenous interference. On the other hand, the low colonization resistance allows the interventional modification of the early microbiota by oral administration of beneficial bacteria. With time, additional bacterial species colonize the intestine and increase the diversity of the microbiota composition. In combination with the influence of genetic determinants and environmental factors, this ultimately leads to the generation of a mature and highly diverse enteric microbiota that remains relatively stable throughout life. In this chapter we will discuss the establishment of the enteric microbiota after birth and the current understanding of its influence on disease susceptibility. We will also address interventional strategies that particularly during early life might be able to modify the microbiota and improve long-term health.