微生态学是研究微生物与其宿主之间关系的科学。人体与外界相通的器官,都有微生物定居,正常情况下和人体共生,对人体无害。正常菌群长期定居于人体,在正常情况下对人体无害的微生物称正常微生物群或正常菌群。正常菌群存在于人体体表和与外界相连的腔道,如皮肤、口腔、鼻咽腔、外耳道、肠道、泌尿生殖道。 Microbiology is a science that studies the relationship between microorganisms and their hosts. The organs that the human body communicates with the outside world all have microorganisms to settle down. Under normal circumstances, they co-exist with the human body and are harmless to the human body. Normal long-term colonization of the human body in the human body, under normal circumstances harmless microorganisms called normal micro-organisms or normal flora. Normal flora exists in the human body surface and connected with the outside world such as the skin, mouth, nasopharyngeal cavity, external auditory meatus, intestine, genitourinary tract.