Investigating the number of Lactobaccilus, Escherichia coli and Prevotella in fecal microbiota of adenomatous polyposis and colorectal cancer patients

Abstract

Background: Colorectal cancer is the second most common cancer in the world which is mainly caused by epigenetic and environmental factors. Among these epigenetic factors, gut microbiota is an important one. Although it has not been proved a unique group of bacteria correlated with colorectal cancer, these findings have generally demonstrated differences between healthy and disease gut microbiome in population. Actually, the identification and investigation of intestinal microbiota in early detection of colorectal cancer have been highlighted in new researches and studies. Herein, in the current study, we aimed to evaluate the number of selected gut bacteria including Lactobacillus and Escherichia coli and Prevotella in the fecal specimens of adenomatous polyposis patients, colorectal cancerous cases in compared to normal participants in terms of estimating important role of gut microbiota during colorectal cancer initiation and progression. Methods: The current research was a case-control study. Fecal samples were provided from 31 healthy individuals, 42 adenomatous polyposis patients and 20 colorectal cancer cases that were referred to Taleghani Hospital, Tehran, Iran, from August 2016 to August 2017 for colorectal cancer screening tests. Fecal samples were collected to analyze intestinal bacteria including, Lactobacillus, Escherichia coli, and Prevotella by absolute quantitative real-time polymerase chain reaction (PCR). The number of these gut bacteria was precisely determined by this method of real-time PCR. Results: Higher number of Prevotella with 24.6 CT number (P<0.005) and E.coli with 20.4 CT number (P<0.015) were achieved in colorectal cancer cases and adenomatous polyposis patients in contrast to samples from normal individuals. On the contrary, the opposite range was observed for the quantification of Lactobacillus and greater numbers of bacteria (CT=28.6) were detected in normal, compared to the colorectal cancer cases and adenomatous polyposis (P<0.001). Conclusion: The gut microbiota composition of individuals with colorectal cancer and adenomatous polyposis differs from that of healthy individuals, and the higher numbers of pathogenic microbiota versus beneficial microbiota present in those with colorectal cancer and adenomatous polyposis. In contrast, healthy individuals have higher numbers of beneficial gut microbiota than pathogenic microbes. These findings need more experimental analysis and investigation to better clarify.

Keywords

• adenomatous polyposis
• case-control studies
• colorectal neoplasms
• gastrointestinal microbiome