Molecular mechanisms by which ClbA, ClbB and ClbQ genes component of colibactin contribute to Escherichia coli-induced colorectal tumorigenesis

Background. The importance of Escherichia coli bacteria is highlighted by being a pathogen and encoding genes that produce toxins that contribute to the occurrence of tumors in colon and rectal cancer. Aim of study. Molecular detection of the most important genes produced by Escherichia coli bacteria and their role in causing colon and rectal tumors. Methods. 80 different samples were collected from patients with colon and rectal cancer and were clinically examined in the endoscopy unit inside Al-Sadr Teaching Hospital in Basra Governorate during the period from March 2022 to December 2023. Results. Escherichia coli bacteria were isolated and diagnosed and were molecularly diagnosed by 16S rRNA sequencing. As for the genes ClbA, ClbB, and ClbQ, they were diagnosed using special primers and real-time PCR technology. CT values showed gene expression for all genes at high levels among infected individuals and lower than in the group of healthy individuals and were not detected in the second group of healthy individuals. Conclusion. The results revealed a frequency of Escherichia. coli in infected individuals, accompanied by an increased expression of the virulence genes CblA, ClbB and ClbQ that encode colibactin. Real-time PCR analysis confirmed these results.