Prevalence and Expression of Cytolethal Distending Toxin Genes in Escherichia coli Isolates from Iraqi Patients

Abstract

Escherichia coli is a Gram-negative bacterium that possessesvarious virulence factors. One such factor is Cytolethal Distending Toxin (CDT),a genotoxin encoded by cdt genes. These genes have multiple variants and are classified into five types. Each CDT toxin is composed of three subunits-CDT-A, CDT-B, and CDT-C. This genotoxin induces DNA damage and leads to cell death. This study aims to detect the presence of the cdt gene and its expression in E. coli isolates collected from different sources,including urine, colon cancer tissue, wounds, and stool samples from individuals of various ages and sexes. One hundred twenty samples were collected and diagnosed using traditional biochemical tests and the Polymerase chain reaction technique. Only sixty isolates were confirmed as E. coli. These isolateswere further analyzed using PCR to detect the presence of the cdt gene. The results showed that only three samples contained the cdt gene.While six samples exhibited their expression. This research indicates the low frequency and prevalence of the cdt gene in E. coli and the presence of variant types of this genotoxin.