Antimicrobial resistance and pathogenicity islands in mucosa-associated Escherichia coli in colorectal cancer patients

Abstract Colorectal cancer (CRC) is one of the most prevalent adult cancers. Escherichia coli may contribute to CRC development and progression through its virulence factors and inflammatory pathways. E. coli acquires antibiotic resistance easily; however, the antibiotic resistance in mucosa-associated E. coli in CRC is still undefined. This study aims to determine the prevalence and distribution of pathogenicity islands (PAI) and antibiotic resistance in mucosa-associated E. coli i solated from CRC patients compared to colorectal adenoma (CRA) and the healthy control group. This cross-sectional study included 63 mucosa-associated E. coli isolated from colorectal biopsies of 21 CRC, 7 CRA and 35 healthy control individuals. Antibiotic susceptibility was performed by the disk diffusion method. PAI (pks, PAI I-IV536, PAI I-IICFT073 and PAI I , IIJ96 ) and Beta-lactamase genes (carbapenemase genes, CTX-M gene) were detected by PCR. More than one PAI was detected in (90.5%, 57%, 68.5%,) of mucosa-associated E. coli isolated from CRC, CRA, and control, respectively. The pks and PAI IV536 were the most common PAI among our isolates. There is no significant difference in antibiotic resistance between pKs- positive E. coli isolates and the pks- negative -E. coli isolates. Resistance to Ampicillin, Ceftazidime, Aztreonam, Trimethoprim-sulfamethoxazole and Cefepime was significantly higher in mucosa-associated E. coli in CRC patients than in normal subjects. NDM and OXA48 were the most common carbapenemase genes detected in all studied groups. The CTX-M gene was detected in 41.3% of all the isolated mucosa-associated E. coli . High prevalence of multiple PAIs and multiple drug resistance in mucosa-associated E. coli in both colorectal neoplasia and normal individuals. Significantly higher prevalence of PAI IV536 and resistance to Ampicillin, Ceftazidime, Aztreonam, Cefuroxime, Trimethoprim- sulfamethoxazole and Cefepime in mucosa-associated E. coli of CRC compared to healthy subjects. We recommend raising awareness of antibiotic resistance, strategies to prevent the spread of antibiotic resistance, such as surveillance, improving sanitation and further study to assess the effect of antibiotic use on colonic E. coli in CRC.