The frequency of cyclomodulin encoding genes in mucosa-associated Escherichia coli isolated from patients with colorectal cancer and non-cancer patients

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. Materials: At two university-affiliated hospitals in Tabriz, 98 patients, 48 with CRC and 48 without, were studied over the course of 15 month. Fresh biopsy specimens obtained by colonoscopy were used to identify mucosa-associated E. coli isolates after mucolysis. To identify the genotypes of E. coli isolates, composed colonies in each sample were typed using Enterobacterial repetitive intergenic consensus-based PCR (ERIC-PCR). The strains were then classified into phylogroups using quadruplex PCR method. The PCR method was used to examine for the presence of cyclomodulin and other virulence factors encoding genes. The strains were also tested for biofilm formation using a microtiter plate assay.

Results: CRC patients had more mucosa-associated E. coli than the control group (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 and other virulence factors encoding genes in the CRC patients was higher than the control group. Around 38.33% of E. coli strains from CRC samples were able to form biofilms, compared to 17% of the strains from the control group (p < 0.05).