Updated method: NMKL 164, Escherichia coli 0157. Detection in food and animal feed
Escherichia coli O157 (H7 or H-) comprising stx genes and eae gene is a pathogenic E. coli belonging to the Shigatoxin-producing E. coli (STEC) pathogroup and may cause severe infections in humans.
Humans are usually infected through contaminated food or direct contact with animals or the environment such as contaminated water. STEC O157 may survive well in different types of foods, and the infectious dose is low.
This method describes the qualitative determination of E. coli O157 in food and animal feed. It is also applicable for primary production samples (animal fecal samples and environmental samples), although the performance of the method on this matrix is not validated.
This updated method now includes information on sorbitol-fermenting E. coli O157 (SF E. coli O157). In addition, obligatory determination of presence of the major virulence genes stx and eae by a reference laboratory has been added. It is mandatory to test isolates of E. coli O157 for the presence of stx and eae genes as E. coli O157 without virulence factors are occasionally isolated from samples. A protocol for determination of the genes is not included in the present method as this should be carried out by a reference laboratory. A new Annex 2 has been added, describing the method for analysis of samples from primary production (i.e. fecal samples and environmental samples from primary production).