Normal Values for Fecal Microbial Composition
May 10, 2022
Source: Cainiu Health
Dr. Cheng Yicheng
Introduction
Stool contains a wide variety of bacteria, each present in different normal proportions. The majority are commensal (normal) flora. For example, enterococci and Escherichia coli together account for approximately 80% of the fecal bacterial population, whereas Proteus species and yeasts constitute no more than 10% of the total bacterial count. The ratio of bacilli to cocci in stool is roughly 1:10. Normal intestinal microbiota primarily include Bacteroides, Lactobacillus, Enterococcus, and a small number of other bacterial species.
Eating, drinking, defecation, and urination are fundamental physiological needs for everyone. Among these, stool serves as a crucial “barometer” of health—careful observation can even aid in early disease detection. Stool contains a wide variety of bacteria, each normally present in distinct proportions. So, what are the normal reference ranges for fecal bacterial composition?
Normal Fecal Microbial Composition
Stool harbors numerous bacterial species, each with its own typical proportion under healthy conditions. The majority consist of commensal (normal) flora. For instance, enterococci and Escherichia coli together account for approximately 80% of the total fecal bacteria; while Proteus species and yeasts collectively constitute no more than 10%. The ratio of bacilli to cocci in stool is roughly 1:10.
A healthy gut microbiota primarily comprises Bacteroides, Lactobacillus, Escherichia coli, and Enterococcus, along with smaller populations of other organisms such as Staphylococcus aureus, Pseudomonas aeruginosa, Paracolon bacillus (now classified under Enterobacter or related genera), Clostridium perfringens, Proteus species, and Candida albicans. Under normal circumstances, these microorganisms coexist in a state of mutual dependence and restraint, maintaining ecological balance—including stable population sizes and proportional distributions. If abnormalities are suspected, it is advisable to seek evaluation and treatment at a reputable large hospital to identify the underlying cause of current symptoms and initiate targeted therapy. In cases of intestinal dysbiosis, identifying and addressing the root cause is essential before initiating corrective measures.
During routine stool examinations, clinicians assess the quantities of various bacterial species in the sample to determine whether an intestinal infection is present—and, if so, which specific pathogens are involved. Patients should ensure adequate rest, avoid staying up late, and refrain from excessive physical or mental exertion. We hope this information proves helpful. Wishing you optimal health and a joyful life!
