人自胎儿出生、生长、发育、成熟,直到死亡,无不与微生物休戚相关。在婴儿出生后几小时,消化道便结束无菌状态开始有细菌侵入,定居,繁殖。正常人肠道内存在的各种细菌,其种类、数量以及占据的位置都是相对稳定的。它们互相适应,互相制约,共同形成一个微生态系统。这类细菌我们称为正常菌群,对人体有益无害,而且是必不可少的生 People born from the fetus, growth, development, maturity, until the death, are all associated with microorganisms. A few hours after the baby is born, the digestive tract ends with aseptic conditions beginning with bacterial invasion, colonization and reproduction. The variety of bacteria present in the gut of normal humans is relatively stable in terms of their type, quantity, and occupancy. They adapt to each other, restrict each other and work together to form a micro-ecosystem. We call these bacteria normal flora, beneficial and harmless to the human body, but also essential to students