Virulence genes and pulsed-field gel electrophoresis profiles of Shiga toxin-producing isolated from different food samples and patients with acute diarrhea.

BACKGROUND AND OBJECTIVES

O157: H7 is one of the most important causes of hemorrhagic colitis, and hemolytic uremic syndrome. The present study aimed to isolate O157: H7 from foods and patients with hemorrhagic colitis, and identify Shiga toxin genes, phylogenetic comparison, and antibiotic resistance of the isolates.

MATERIALS AND METHODS

In total 400 samples, including patients stool and food were taken in Isfahan-Iran province. Phenotypic tests and PCR were performed to identify Shiga toxin-producing . The isolated strains were compared phylogenetically by PFGE. Agar disk diffusion was performed to identify the antibiotic resistance of the isolates.

RESULTS

Totally, 5 isolates of fecal samples were O157, but only 2 isolates carried H7 gene. Also, 9 isolates of O157 were isolated from food samples that 3 isolates were O157: H7. The isolates carried and genes. Also, non-O157: H7 identified from samples that contained genes. The highest susceptibility to imipenem and the highest resistance to ampicillin and ciprofloxacin were observed. There was a similarity of 100% between the O157: H7 strains isolated from patients and raw milk and minced beef samples.

CONCLUSION

Serotypes other than the O157 of are more prevalent in patients and food. The O157: H7 isolates from patients had 100% genetic similarity with minced meat and cow milk isolates, which indicates cattle are the most important reservoir of this bacterium in Iran.