Shiga (vero) toxin producing Escherichia coli in various types of food stuffs; virulence factors, O‐serogroups and antimicrobial resistance properties

Abstract

AbstractThe aim of the present study was to determine the incidence of Shiga toxin producing Escherichia coli, its virulence factors, O‐serogroups and antimicrobial resistance properties in various types of food stuffs in Iran. All samples were cultured and those that were E. coli positive were subjected to PCR. Of 801 samples studied, 123 (15.35%) were positive for STEC strains. Samples collected in summer season had the higher prevalence of bacteria (49.59%). Beef meat was the most commonly contaminated sample (24.28%). The stx1 was the most commonly detected, while ehly was the least. The most commonly detected serogroups in the STEC strains recovered from the food samples were O157 (27.64%) and O26 (21.95%). The serogroup of 17.07% of STEC strains cannot be detected by means of the O‐serogroup primers. The most commonly detected antibiotic resistance genes were blaSHV (47.15%) and aadA1 (44.71%). STEC strains of our investigation harbored the highest levels of resistance against ampicillin (100%), gentamycin (70.73%) and tetracycline (62.60%). Observation of proper monitoring, principles of food hygiene and accurate antibiotic prescription reduce the risk of diseases caused by STEC strains in human.Practical applicationsWe found E. coli bacteria with defined pathotypes which originates mainly from human and animal sources in various types of food samples of Iranian markets. We also identified a large numbers of virulent and resistant strains of E. coli with higher prevalence of stx1 and eaeA gene, O157 and O26 serogroups, CITM and aac(3)‐IV antibiotic resistance genes and resistance to ampicillin, penicillin and gentamycin antibiotics. Beef meat had the highest prevalence. Simultaneous presence of stx1 and eaeA and stx2 and eaeA virulence factors in some strains of E. coli bacterium in food stuffs indicated the important public health problem. Using from microbiological tests can contribute to reducing the microbial load in food stuffs. Controlling sources of human and animal fecal pollution, such as managing the quality of primary ingredients, staffs and devices are other approaches to reduce the prevalence of STEC in food stuffs. Using from the disk diffusion method and avoiding from the irregular and excessive prescription of antibiotics are two important approaches to reduce the levels of antibiotic resistance.