Probiotics in pediatrics

Probiotics are defined to be non-pathogenic strains of organism that are incorporated into the diet to modify gut microbial ecology, leading to beneficial structural and functional changes in the gut. Some probiotics may serve as a barrier for the colonization of pathogens to prevent disease and enhance the immune system. In addition, some may carry out metabolic functions such as helping the fermentation of nondigestible fibres, and storing energy in the form of short-chain fatty acids. Of all the types of gut microbiota, Bifidobacteria and Lactobacilli are considered the two most essential bacteria beneficial to human health while Staphylococci and Clostridia are considered pathogenic to human health. Organisms that are considered as probiotics remain viable even after culturing, modification, and storage before ingestion. They are not killed during digestion, and ultimately adhere to the epithelium in the gut. As a consequence, the host may gain clinical health benefits, such as the reduction in antibiotic-associated diarrhea and allergies in infants. The microbiome, which is composed of ecosystems within and on the human body, is necessary for infants in the development of the gut-associated lymphoid tissue (GALT), an essential prerequisite for a normal immune system.

At birth, the infant's intestines are free of bacteria, but bacteria starts to colonize within the intestine quickly after birth. Facultative aerobes are the first to colonize the intestine in infants. However, as time goes by, these facultative aerobes start to deplete the oxygen store within the infant's intestine, making the intestine a favorable environment to harbor anaerobes. Overall, an infant's intestine is mainly colonized by enterobacteria during the first two days after birth.

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