Virulent Bacteria as A Co-factor of Colon Carcinogenesis: Evidence from Two Monozygotic Patients

Colorectal carcinoma (CRC) is a common disease with a poor prognosis. CRC results from the accumulation of DNA alterations in colonocytes through a multistage carcinogenesis process. Most CRCs are related to the environment, which influences microbiota composition in the colon. Here we report the analysis of the gut microbiota of two monozygotic twin sisters, one of whom suffering from advance colorectal tumor-infiltrated by immunotolerant T cells. Comparative analysis highlights the profound disequilibrium of the composition of the gut microbiota of CRC-displaying twin with overexpression of virulent bacteria such as E. coli, Shigella, and Clostridium species in the CRC patient's feces in contrast with low level of bacterial species such as Faecalibacterium and Akkermansia usually enriched in the healthy adults' microbial flora at the expense of an over-representation of pathogenic bacterial species. The disequilibrium in microbiota of the CRC patient's feces as compared to her monozygotic twin sister is linked with inflammatory and immune cell infiltrate in the patient's tumor tissue.