Evaluation of the SHIGA TOXIN QUIK CHEK after overnight enrichment as screening tool for Shiga toxin-producing Escherichia coli detection in human fecal samples

Abstract

We evaluated the SHIGA TOXIN QUIK CHEK (STQC) on its suitability for Shiga toxin-producing Escherichia coli (STEC) testing on human fecal samples after overnight enrichment. Our in-house PCR-based protocol for STEC detection was used as the standard for comparison. STQC detected all described Shiga toxin subtypes with the only exception of Stx2f. In comparison to PCR, STQC performed with an overall sensitivity of 55.4%, specificity of 100.0%, positive predictive value of 100.0%, negative predictive value of 73.0%, infinite positive likelihood ratio, and negative likelihood ratio of 0.45. We conclude that STQC may not be considered a suitable screening tool for STEC detection in human fecal samples, although it could be useful for laboratories where PCR is not a routine tool for STEC screening yet, subject to the confirmation of negative samples by a reference laboratory with full diagnostic capabilities.