正常人体表与腔道(如口、鼻、咽喉、肠道、眼、泌尿生殖器等)的粘膜上都有细菌存在。这些细菌称之为正常菌群。一般书上很少提到在正常菌群中有厌氧菌或仅提一下伴有厌氧菌的存在,似乎厌氧菌在正常菌群中仅处于很次要的地位,或仅是一个伴随者。事实上并非如此,在正常菌群中厌氧菌远多于需氧菌或兼性厌氧菌。以现代厌氧技术检查,每1克齿垢或粪便中可含有厌氧菌10~(10-11)个,在粪便中厌氧菌的菌数为大肠 Normal human body surface and cavity (such as mouth, nose, throat, gut, eye, genitourinary, etc.) have mucous membrane bacteria. These bacteria are called normal flora. It is seldom mentioned in general books that there is anaerobic bacteria in the normal flora or only the presence of anaerobic bacteria. It seems that the anaerobic bacteria are only in a secondary position in the normal flora or only one accompaniment By. In fact, not so much in the normal flora anaerobic bacteria far more than aerobic bacteria or facultative anaerobes. To modern anaerobic technology check, every 1 gram of tartar or manure can contain anaerobic bacteria 10 ~ (10-11), in the feces of anaerobic bacteria in the large intestine