Scientific Principal of the Test
PDX-STEC contains selective agents to prevent the growth of competitive microflora while providing nutrients for growth of the resistant STEC and Salmonella. Salmonella and STEC are differentiated and identified by plating onto commercial selective, differential agar media such as CHROMagar™ and modified Rainbow® Agar products. STEC positive colonies appear as mauve on CHROMagar™ STEC, and Salmonella positive colonies appear as mauve colored colonies on CHROMagar™ Salmonella Plus. STEC positive colonies appear as different shades from cream to mauve on Rainbow® agar. Isolated presumptive STEC and Salmonella colonies can be confirmed using commercial lateral flow immunoassay tests for shiga toxins and Salmonella poly-O antigen. Colonies can also be confirmed using the appropriate probes and primers in qPCR analyses.
Time to Detection
Time to detection is an important parameter of any pathogen detection method particularly when testing end product. Sampling the PDX-STEC enrichment after six to eight hours incubation at 42 degrees C permits detection of virulence markers, stx and eae by PCR analysis. In this manner detection of STEC is achievable within a single shift.