Methods for detecting enterohaemorrhagic Escherichia coli in food

Enterohaemorrhagic Escherichia coli (EHEC) serogroup determines worldwide foodborne illnesses and remains one of the major concerns for the population and for the food industry. These strains, indeed, determine gastrointestinal disease varying from diarrhoea to haemorrhagic colitis, haemolytic uraemic syndrome, and thrombotic thrombocytopaenic purpura. Classic detection methods are based on specific enrichment, often coupled with immunomagnetic separation system, specific media, and different immunoassays. Molecular detection methods, based on DNA probes and PCR, are used to detect the virulence genes and the specific genes associated to the serogroups. Most of the research is focused on E. coli O157:H7, for which the validated standard method ISO 16654/2001 is applied. Regarding the methods used for E. coli non-O157, it is interesting to highlight the existence of the draft of the European Committee for Standardization, which in the near future might constitute the first standard for non-O157 EHEC. This paper describes the state-of-the-art laboratory methods and commercial kits for detecting strains of EHEC vehiculated with foods.