High Prevalence of Escherichia coli Harboring Colibactin Genes in Colorectal Cancer Patients in Qom, Iran: A Case-Control Study
Colibactin Genes in Escherichia coli from CRC Patients
Keywords:
Colibactin, Escherichia coli, Colorectal Cancer, pks Island, IranAbstract
Introduction:Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide. Emerging evidence implicates genotoxin-producing bacteria, particularly Escherichia coli harboring the pks genomic island, in CRC pathogenesis. This study aimed to determine the frequency of clbN and clbB genes (encoding colibactin) in E. coli isolates from CRC patients and healthy controls in Qom, Iran.
Method: In this case-control study, 200 paraffin-embedded biopsies (136 CRC cases and 64 healthy controls) were collected from patients referred to medical centers in Qom province between April 2018 and May 2019. E. coli was identified using culture and biochemical tests. The presence of clbP, clbN, and clbB genes was detected by PCR. Demographic data and risk factors were recorded. Data were analyzed using SPSS v22.0, with chi-square, Fisher's exact test, and logistic regression to calculate odds ratios (OR) with 95% confidence intervals (CI).
Result: E. coli was significantly more prevalent in CRC biopsies (79/136, 58.1%) compared to controls (11/64, 17.2%; p < 0.001). Among CRC patients, the frequencies of clbB, clbN, and clbP were 12.5%, 11.8%, and 8.1%, respectively, versus 6.2%, 4.6%, and 1.6% in controls. While no individual gene reached statistical significance, the combined presence of clbN and clbB was associated with a 2.5-fold increased odds of CRC (OR = 2.54; 95% CI: 1.02–6.31; p = 0.04). Gender distribution showed no significant differences.
Conclusion: The high prevalence of E. coli in CRC tissues and the increased odds of CRC associated with clbN/clbB co-carriage suggest a potential contributory role of colibactin-producing E. coli in CRC pathogenesis. These findings underscore the need for larger prospective studies and functional assays to confirm causality.
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