Method for determining the presence or absence of shiga toxin-producing Escherichia coli (STEC) in a food sample

摘要

The present invention relates to a method which will lead within a shorter period of time to reliable results with respect to the presence or absence of pathogenic STEC (Shiga toxin-producing Escherichia coli) in food samples. The method comprises - incubating the food sample in a culture medium enabling growth of E. coli to obtain an E. coli stock medium; - performing a lysis of the E. coli in the stock medium to obtain a sample solution comprising E. coli DNA; and - subjecting the sample solution to a first series of polymerase chain reactions (PCR), using primers to amplify the following E. coli genes or fragments thereof: €¢ stx1 and/or stx2 encoding Shiga toxin 1 and Shiga toxin 2, respectively, €¢ for each STEC serogroup to be determined, the subtype of the eae gene of that serogroup encoding an intimin, and €¢ for each STEC serogroup to be determined, a biomarker gene specific for that serogroup; and, in case that stx1 and/or stx2 as well as the eae gene and the specific biomarker gene for at least one serogroup are amplified in the first series of PCRs: - verifying the presence of the one or more specific serogroups of STEC by performing a second series of PCRs on concentrates of the E. coli stock medium and, optionally, a third series of PCRs on single E. coli colonies derived from the concentrates.