Mucosa-Associated Escherichia coli Producing Cyclomodulin toxins in Colon Cancer and intestinal inflammatory Patients

Background: Colorectal cancer (CRC) is the third most common cause of death. In the human intestinal tract, some Escherichia coli strains produce cyclomodulin toxins. This study aimed to determine the frequency of cyclomodulin-encoding genes in E. coli isolates from patients with CRC and inflammatory bowel disease (IBD) compared to healthy subjects.
Materials & Methods: A total of 120 E. coli strains were isolated from colonic mucosa samples during 2016-2017 from Hamadan, Iran. E. coli isolates were identified using biochemical tests. Phylogroups of E. coli isolates and cyclomodulin toxin-encoding genes were identified by PCR. The results were analyzed by SPSS software.
Findings: The predominant E. coli phylogroups were A (52.5%), B2 (52.5%), and A (55%) in the CRC, IBD, and healthy groups, respectively. E. coli isolates harboring the pks (32.5%) and cnf1 (27.5%) genes belonged to phylogroup B2 (p< .001), and isolates harboring the pks gene were more prevalent in CRC patients (30%). The cnf3 gene had the highest frequency (30.8%) in the cnf gene family. The highest prevalence of cnf1 (27.5%) was observed in E. coli phylogroup B2, the highest prevalence of cdt4 (58.3%) was in phylogroup B1, and the highest prevalence of cif (52.5%) was strongly related to phylogroup B2.
Conclusion: The presence of cyclomodulin toxin-encoding genes in E. coli isolates was not associated with CRC, and no statistical difference was observed in the level of cyclomodulin-encoding genes in E. coli isolates. On the other hand, there is no information about the critical time of host-microbe interaction for tumorigenesis.