Evaluation of the SHIGA TOXIN QUIK CHEK and ImmunoCard STAT! EHEC as screening tools for the detection of Shiga toxin in fecal specimens

- SHIGA TOXIN QUIK CHEK identified all Shiga toxin subtypes except Stx2f.
- ImmunoCard STAT! EHEC identified all Stx1 subtypes but only 3 of 7 Stx2 subtypes.
- SHIGA TOXIN QUIK CHEK able to detect Shiga toxin directly in fecal specimens.

In this study we evaluated the performance of the SHIGA TOXIN QUIK CHEK (Techlab®, Blacksburg, VA) and the ImmunoCard STAT! Enterohaemorrhagic E. coli (EHEC) (Meridian BioScience, Cincinnati, OH, USA) assays as methods for qualitatively detecting the presence of Shiga toxin in human fecal specimens. A multiplex PCR for the detection of stx1 and stx2 was used as the standard for comparison. The SHIGA TOXIN QUIK CHEK detected all known Shiga toxin subtypes with the exception of Stx2f, while the ImmunoCard STAT! EHEC was unable to identify four of the seven Stx2 subtypes, including Stx2b and Stx2d. When compared to multiplex PCR based on Shiga toxin gene presence alone both assays demonstrated 100% specificity, and gave sensitivity values of 50.0% and 41.2% respectively. Correlation between each assay and the multiplex PCR was calculated by the use of kappa, with both assays exhibiting a moderate level of agreement.