Colonization of the gut mucosa of colorectal cancer patients by pathogenic mucosa-associated Escherichia coli strains.

Some strains of Escherichia coli are known to be involved in the pathogenesis of colorectal cancer (CRC). The aim of current study was to compare the general characteristics of the E. coli from CRC patients and healthy participants. A total of 96 biopsy samples from 48 CRC patients and 48 healthy participants, were studied. The clonality of the E. coli isolates was analyzed by Enterobacterial repetitive intergenic consensus-based PCR (ERIC-PCR) method. The strains were tested by PCR to determine the prevalence of different virulence factors. According to the results of ERIC-PCR analysis, (from the 860 E. coli isolates) 60 strains from CRC patients and 41 strains from healthy controls were identified. Interestingly, the majority of the strains of both groups were in the same cluster. Enteropathogenic E. coli (EPEC) was detected significantly more often in CRC patients (21.6 %) than in healthy participants (2.4 %) (p < 0.05). The Enteroaggregative E. coli (EAEC) was found in 18.33 % of the strains of CRC patients. However, other pathotypes were not found in the E. coli strains of both groups. Furthermore, all the studied genes encoding for virulence factors seemed to be more prevalent in the strains belonging to CRC patients. Among the virulence genes, the statistical difference regarding the frequency of fuyA, chuA, vat, papC, hlyA and cnf1 genes was found significant (p < 0.05). In conclusion, E. coli strains that carry extraintestinal pathogenic E. coli (ExPEC) and diarrheagenic E. coli (DEC) multiple virulence factors colonize the gut mucosa of CRC patients.

Escherichia coli and Colorectal Cancer: Unfolding the Enigmatic Relationship.

Colorectal cancer (CRC) is one of the deadliest cancers in the world. Specific strains of intestinal Escherichia coli (E. coli) may influence the initiation and development of CRC by exploiting virulence factors and inflammatory pathways. Mucosa-associated E. coli strains are more prevalent in CRC biopsies in comparison to healthy controls. Moreover, these strains can survive and replicate within macrophages and induce a pro-inflammatory response. Chronic exposure to inflammatory mediators can lead to increased cell proliferation and cancer. Production of colobactin toxin by the majority of mucosa-associated E. coli isolated from CRC patients is another notable finding. Colibactin-producing E. coli strains, in particular, induce double-strand DNA breaks, stop the cell cycle, involve in chromosomal rearrangements of mammalian cells and are implicated in carcinogenic effects in animal models. Moreover, some enteropathogenic E. coli (EPEC) strains are able to survive and replicate in colon cells as chronic intracellular pathogens and may promote susceptibility to CRC by downregulation of DNA Mismatch Repair (MMR) proteins. In this review, we discuss current evidence and focus on the mechanisms by which E. coli can influence the development of CRC.

Epidemiological and clinical characteristics of inflammatory bowel disease in patients from northwestern iran.

BACKGROUND: There are few reports from Iran about the epidemiology and clinical features of inflammatory bowel disease (IBD). This study aims to determine the epidemiologic profile and clinical features of IBD in Northwest Iran referral centers. METHODS: In a cross-sectional setting, we evaluated 200 patients with definitive diagnoses of IBD who referred to Tabriz educational hospitals during the period of 2005 to 2007. Demographic characteristics as well as patients' clinical profiles were evaluated. Disease activity and severity were determined by the Crohn's Disease Activity Index and Truelove and Witt's classification of ulcerative colitis (UC). The related probable demographic factors were tested. RESULTS: Of the 200 IBD patients, 183 (91.5%) were diagnosed with UC and 17 (8.5%) with Crohn's disease (CD). There was a positive first degree relative of IBD in 10.9% of UC and 11.8% of CD patients. Abdominal pain was the primary presenting symptom in 25.7% of UC patients and in 58.8% of those with CD. Among UC patients, left-sided colitis was the main feature (52.5%); while in patients with CD, colon involvement was predominant (52.9%). There was no significant contributor for activity or severity of disease noted among demographic factors. CONCLUSION: The occurrence of UC was much higher than CD. The onset of IBD occurred in younger ages with a predominance in males. Left-sided colitis in UC and colon involvement in CD was common. Mostly, the pattern of IBD was mild to moderate with good response to pharmacotherapy. Disease activity and severity were unaffected by demographic features.