Our O157:H7 iDDS probe assay detects the +93 SNP in the uidA gene of the highly pathogenic E. coli variant, O157:H7. The +93 SNP is highly conserved in O157:H7 and O157:H- strains that produce shiga toxins and serves as an accurate identification marker for these severe pathogens.
The iDDS probe assays shows superior performance over a TaqMan MGB probe, designed and recommended by the FDA, that targets the same SNP variant. Using the concentrations and PCR conditions recommended by the FDA for their O157:H7 TaqMan MGB probe assay, we tested both probes over a series of annealing temperatures ranging from 63 to 40ºC. Our iDDS probe assay showed stable discrimination over a 23ºC annealing temperature range, whereas the TaqMan MGB probe began to show false-positives after the annealing temperature was decreased by 3ºC.