Analysis of tellurite resistance gene, tehA, in Shiga toxin-producing Escherichia coli O157

Resistance to potassium tellurite (PT) is an important indicator in isolating Shiga toxin-producing Escherichia coli O157:H7. Common resistance determinant genes are encoded in a ter gene cluster. We found a O157:H7 isolate that does not carry ter but is resistant to PT. One nonsynonymous mutation was found in another PT resistance gene, tehA, through whole-genome sequence analyses. To elucidate the contribution of this mutation to PT resistance, complementation of tehA and its related gene, tehB, in isogenic strains, and quantitative RT-PCR were performed.