Obesity in school-aged children and its correlation with Gut E.coli and Bifidobacteria: a case-control study

Background: To determine the correlation between obesity in school-aged children and imbalance of gut microbes by examining the ratio change of intestinal Bifidobacteria and E. coli in obese children compared to non-obese controls. Methods: A hospital-based 1:1 case-control study was performed. Fecal samples of the subjects were collected for DNA extraction and analyzed by quantitative real-time PCR (qPCR) to determine the copy number of Bifidobacteria and E. coli. The ratio of two microbes (B/E) was then calculated and statistically analyzed. Results: Subjects of the obesity group and control group showed no significant difference in age, gender or height (P > 0.05); whereas they had significant differences in body weight and BMI. Copy numbers of Bifidobacteria and E. coli per gram of wet fecal samples were first determined using qPCR in both obese and normal groups, which were further used for the calculation of B/E ratio. We found that B/E ration in the two groups showed significant difference (P< 0.05). Corrected chi(2) test was performed for the two groups against B/E < 1, and it was found that there was a positive correlation (OR = 719.2, OR 95% C.I. = 81.57-6341.18) between B/E ratio decrease with childhood obesity. Conclusions: The obese children have a lower amount of Bifidobacteria and higher amount of E. coli (smaller B/E ratio) compared to normal non-obese children. It was suggested that obesity in children may be associated with the imbalance of gut microbes.