Abstract
Accumulating evidence indicates that specific strains of mucosa-associated Escherichia coli (E. coli) can influence the development of colorectal carcinoma. This study aimed to investigate the prevalence and characterization of mucosa-associated E. coli obtained from the colorectal cancer (CRC) patients and control group. At two referral university-affiliated hospitals in northwest Iran, 100 patients, 50 with CRC and 50 without, were studied over the course of a year. Fresh biopsy specimens were used to identify mucosa-associated E. coli isolates after dithiothreitol mucolysis. To classify the E. coli strains, ten colonies per sample were typed using enterobacterial repetitive intergenic consensus-based PCR (ERIC-PCR). The strains were classified into phylogroups using the quadruplex PCR method. The PCR method was used to examine for the presence of cyclomodulin, bfp, stx1, stx2, and eae-encoding genes. The strains were tested for biofilm formation using the microtiter plate assay. CRC patients had more mucosa-associated E. coli than the control group (p < 0.05). Enteropathogenic Escherichia coli (EPEC) was also found in 23% of CRC strains and 7.1% of control strains (p < 0.05). Phylogroup A was predominant in control group specimens, while E. coli isolates from CRC patients belonged most frequently to phylogroups D and B2. Furthermore, the frequency of cyclomodulin-encoding genes in the CRC patients was significantly higher than the control group. Around 36.9% of E. coli strains from CRC samples were able to form biofilms, compared to 16.6% E. coli strains from the control group (p < 0.05). Noticeably, cyclomodulin-positive strains were more likely to form biofilm in comparison to cyclomodulin-negative strains (p < 0.05). In conclusion, mucosa-associated E. coli especially cyclomodulin-positive isolates from B2 and D phylogroups possessing biofilm-producing capacity colonize the gut mucosa of CRC patients.
Highlights
Colorectal cancer (CRC) is the world’s third most common cancer and the second leading cause of cancer death [1].Because of its high morbidity and mortality rate, CRC is an important public health issue [2]
E. coli Strains in CRC and Control Group Specimens. e investigation of the presence of E. coli isolates showed that the number of specimen without E. coli was remarkably higher in control specimens (20%, n 10/50) than in those with CRC patients (4%, n 2/50), P 0.028
As some specimens carried more than one E. coli strains, a total of 65 E. coli strains from CRC patients and 42 E. coli strains from the control group were taken into the study (Figure 1)
Summary
Colorectal cancer (CRC) is the world’s third most common cancer and the second leading cause of cancer death [1].Because of its high morbidity and mortality rate, CRC is an important public health issue [2]. Mutations that occur in tumor suppressor genes, oncogenes, and genes related to DNA repair mechanisms can lead to CRC. E human gut microbiota contains over more than 1,000 microbial species, adding together 1014 microorganisms [4] that play an essential role in many important physiological processes, such as food digestion, metabolism, and immune response [5]. Gut bacteria may be involved in the initiation or progression of sporadic CRC via a variety of mechanisms, including inducing inflammation, generating reactive oxygen species, and producing genotoxins [8]. Considering the fact that E. coli is the most common facultative anaerobic resident in human gut flora, several research studies have shown a strong link between mucosa-associated E. coli and CRC [8, 11,12,13]. Pathogenic E. coli strains are mostly found in the B2 or D phylogroups, while commensal strains are mostly found in groups A and B1 [15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Canadian Journal of Infectious Diseases and Medical Microbiology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
