Isolation, Culture And Identification Of Bacterial Strains From Colorectal Cancer Tissue And Infection Experiment Of Bacteroides Fragilis

Objective:As malignant tumor disease, colorectal cancer (CRC) with high incidence of a disease threats human health, and many researches has showed intestinal flora plays an important role in promoting the occurrence and development of colorectal cancer. In this study, we explore the structure and composition of flora by isolation, cultivation and identification of anaerobes in colorectal cancer tissue. Using the authenticating technology, we obtained the bacteria closely associated with colorectal cancer development, and then we researched the infection ability to KMB17 cells of Enterotoxigenic Bacteroides fragilis.Methods:Collecting the carcinoma tissue of 51 cases of patients with colorectal cancer surgery specimens from 2014 to 2015, we obtained and cultivated the intracellular bacteria under anaerobic conditions. Then we amplified the specificity of 16SrRNA in the bacterial and identified the bacterial species, and identified the core flora on colorectal cancer tissue by the result of the detection rate of isolated bacterial strains. Then we made the Enterotoxigenic Bacteroides fragilis to infect KMB17 cells, to observe the infection status by transmission electron microscope and immunofluorescence observations.Results:we obtained 172 bacterial strains belonging to 35 bacterial species; Escherichia fergusonii, Enterococcus faecalis, Bacteroides fragilis and Bacteroides thetaiotaomicron were the core flora on colorectal cancer tissue with higher detection rate. In the transmission electron microscope and immunofluorescence test results bacteria can be observed within the cell, confirmed Enterotoxigenic Bacteroides fragilis success into intracellular infected KMB17 cells.Conclusion:Pathogenic bacteria or conditional pathogenic bacteria has certain advantages with probiotics on the species and number in colorectal tumor tissue samples, Escherichia fergusonii, Enterococcus faecalis, Bacteroides fragilis,Shigella sonnei and other pathogenic bacteria and conditional pathogenic bacteria may play an important role in the promoting the development process of colorectal cancer; and the Enterotoxigenic Bacteroides fragilis can succeed to infect KMB17 cells and enter the KMB17 cells.