Detection and Characterization of Escherichia coli and Escherichia coli O157:H7 in Human, Animal, and Food Samples from Kirkuk Province, Iraq

This study aims to investigate the prevalence of E. coli and E. coli O157:H7 in 353 samples collected in Kirkuk from human stool, animal feces, raw and pasteurized milk, and beef hamburgers. E. coli was isolated using conventional methods and identified with the Enterosystem Kit 18R. Suspected E. coli O157:H7 were confirmed serologically and tested for antimicrobial resistance and virulence genes (stx1, stx2, eaeA, and hlyA). The overall prevalence rates of 20.4% for E. coli and 7.9% for E. coli O157:H7 were found, with the highest prevalence in human stool. The antimicrobial susceptibility profile of 28 E. coli O157:H7 isolates revealed significant resistance and sensitivity patterns, highlighting important implications for public health. The isolates demonstrated complete sensitivity to gentamicin (100%), while also showing high sensitivity to ciprofloxacin (92.86%), ceftriaxone (85.71%), and amikacin (64.29%). Conversely, the isolates exhibited notable resistance to tetracycline (85.71%), ampicillin (75.00%), sulfamethoxazole (71.43%), and streptomycin (67.86%). All the E. coli O157:H7 strains isolated in this study were positive for stx1 and/or stx2, as well as the eaeA gene, and are referred to as enterohemorrhagic (EHEC) strains. In order to highlight the genotypic variability among the EHEC E. coli O157:H7 isolates, five virulence profiles were identified, with profile III (stx2, eaeA, and hlyA) being the most common (35.7%). This profile was closely associated with diarrheic humans, while profile V (stx1, eaeA) was prevalent in animal feces and products. These findings may raise awareness of the risks associated with this pathogen, helping to reduce the incidence of E. coli-related diseases and to protect human health.