Prevalence of Escherichia coli O157:H7 in Clinical and Food Samples: A Cross-sectional Study

Background and Aim: Escherichia (E.) coli O157:H7 is a virulent bacterial strain known for producing a toxin called Shiga toxin, which can damage intestinal and kidney cells leading to bloody diarrhea and kidney failure. Food poisoning is a significant public health issue worldwide. This study aimed to investigate the prevalence of E. coli O157:H7 in clinical and food samples. Materials and Methods: In this cross-sectional study, 62 food samples, including raw chicken meat, milk, and beef were randomly collected from several supermarkets in different areas of Hamadan City, Iran. Additionally, 62 E. coli strains were collected from various clinical specimens, including wounds, urine, blood, and cerebrospinal fluid, from Besat Hospital in Hamadan, Iran, and analyzed for E. coli O157:H7 contamination. All samples were cultured on specific media, and any suspicious colonies were subjected to PCR for verification of E. coli O157 H7 strain using two target genes. Results: In total, 2 clinical and 8 food samples were positive for E. coli O157:H7 phenotypically. All isolates were positive for the presence of target genes using PCR. The highest frequency was related to contaminated food, particularly beef, with a frequency of 12.9%. Conclusion: The results indicated high prevalence of E. coli O157:H7, especially in beef that was higher than the global average. Therefore, it is necessary to implement more precise controls in production and maintenance processes of food samples.