正常人小肠中有少量细菌,每毫升肠液中含菌量约10~3～10~4个,主要为过路菌。大肠则有大量细菌,每克粪便约含10~7～10~(12)个,90%属经常繁殖的常住菌。其中大肠杆菌为10~6～10~8个,肠球菌为10~5～10~8,类杆菌为10~9～10~(10)个,乳杆菌为10~8～10~(10)个。10%为过路菌,如副大肠杆菌、变形杆菌、绿脓杆菌、肺炎杆菌、葡萄球菌、产气荚膜杆菌以及白色念珠菌等。这些细菌和真菌按上述比例 Normal small intestine in a small amount of bacteria per milliliter intestinal fluid containing bacteria about 10 ~ 3 ~ 10 ~ 4, mainly for bacteria. There are a large number of bacteria in the large intestine, about 10 ~ 7 ~ 10 ~ (12) per gram of feces, 90% of which are often resident bacteria. The number of Escherichia coli was 10 ~ 6 ~ 10 ~ 8, Enterococcus was 10 ~ 5 ~ 10 ~ 8, Bacteroides was 10 ~ 9 ~ 10 ~ 10, Lactobacillus was 10 ~ 8 ~ 10 ~ A 10% of the bacteria, such as Vice Escherichia coli, Proteus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Clostridium perfringens and Candida albicans and so on. These bacteria and fungi in the above ratio