Abstract
Selective plate media supplemented with potassium tellurite, such as sorbitol MacConkey agar with cefixime and potassium tellurite (CT-SMAC) are widely used for isolation of Shiga toxin-producing Escherichia coli (STEC), especially in major O serogroups including O157, O111, O26, O103, O121 and O145. However, there is little information in effectiveness of these plates for minor O-serogroup STEC strains. Here, we evaluated four types of commercial STEC selective plates (CT-SMAC, CHROMagar STEC, XM-EHEC and “KBM” EHEC Chromogenic Medium) using 152 various O-serogroups STEC strains, except for major O serogroups. As a result, 36 strains belonging to 16 O serogroups grew on all four types of plates, and PCR screening showed that all 36 carried the terA associated with tellurite resistance. Of these strains, 27 were eae-positive, and other 9 were eae-negative STEC. The STEC characteristics about the resistance to tellurite as well as the prevalence of the ter operon based on their O serogroups (or O genotypes) reported here may help to choose a suitable selective media on the investigation and the surveillance of STEC.
