Caracteristicile microbiotei în diferite segmente ale tubului digestiv: particularitățile de colonizare și semnificația pentru sănătate

Diverse microbial communities colonize distinct segments of the gastrointestinal tract, influencing human health and pathology. The concentration and composition of the microbiota vary in different parts of the body and digestive tract: 20% in the oral cavity, 15-16% in the oropharynx, 40% in the esophagogastroduodenal region and intestines, 18-20% on the skin, and 2-10% in the urogenital tract. Bacterial colonization is dictated by environmental conditions (aerobic/anaerobic, pH), with most intestinal bacteria being anaerobic, but some segments, such as the cecum, can have high densities of aerobic bacteria. The oxygen concentration along the intestine and in early life determines the bacterial composition, with the first colonizing bacteria being aerobic or facultative anaerobes (Enterobacteria, Enterococci, and Staphylococci). As these consume oxygen, the environment becomes suitable for anaerobic bacteria (Bifidobacterium, Clostridia, Bacteroides). The bacterial community of the digestive tract has coevolved with the human species, establishing mechanisms of beneficial coexistence (commensalism). Proper colonization of the digestive tract immediately after birth is crucial for later health, influenced by the mode of birth, breastfeeding, nutrition, and microbiome modulation by the immune system. This forms the basis for the development of the gastrointestinal tract and immune system and establishes the pattern of the adult microbiome.