Shiga toxin-producing Escherichia coli (STEC) is a major cause of foodborne infections and outbreaks worldwide. STEC in humans may be associated with important diseases, such as hemorrhagic colitis and hemolytic uremic syndrome (HUS). The latter disease causes significant mortality in children and the elderly (1,2). The major STEC virulence factors are Shiga toxins, which are subdivided into 2 types (Stx1 and Stx2) and several subtypes. The stx1 gene is rather homogenous with 3 subtypes (stx1a, stx1c, and stx1d), whereas the stx2 gene is diverse with 7 known subtypes (stx2a, stx2b, stx2c, stx2d, stx2e, stx2f, and stx2g) (3). Epidemiology of various diseases in humans has become complicated in recent years as emerging STEC strains appear to be associated with human diseases (4). Surveillance in recent years shows that stx2f-harboring strains are increasingly associated with diarrhea and sporadic HUS cases in Europe and Japan (5,6,7). In addition, it has been shown that E. albertii, which possesses major Stx2f-STEC properties, can also be considered as an emerging pathogen (8). Among the 7 known stx2 subtypes, Shiga toxin 2f detection can be challenging because most of the genotypic and phenotypic methods fail to detect this subtype (2,9,10). Therefore, validation of diagnostic methods for detection of the emerging Stx2f-producing strains could be invaluable in the clinical setting. We aimed to investigate the capability of 5 widely used generic and/or specific polymerase chain reaction (PCR) based approaches to detect stx2f and compared the limit of detection (LOD) and specificity of the selected assays.

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