ERP Micro December 2019

and reference method confirmed (POD R ) results indicated that there was a statistically significant difference at the 5% level for both methods due to higher recovery by the alternative method (see Discussion , previous section). Discussion The HT Amplification tubes have a reduced size, allowing more amplification tubes to be analyzed per GDS machine run compared to the standard amplification tubes. POD statistical analyses of the samples indicated that for all foods analyzed, there was no statistical difference between the GDS EHEC presumptive using the HT amplification tubes compared to the GDS EHEC confirmed. Method Conclusions For cultural inclusivity, of the 50 inclusivity E . coli O157:H7 isolates, all 50 inclusivity organisms were correctly identified when using the PPMX. For all foods analyzed, there was no statistical difference between the GDS EHEC presumptive compared to the GDS EHEC confirmed when using the PPMX. The method comparison study yielded similar results between alternative and refence method for raw ground beef and green onion. The alternative method (enrichment media) recovered statistically better for frozen finely textured beef and for carcass cloths. Results of these studies also demonstrated that the smaller HT Amplification tube size may be used for the Assurance GDS ® for E . coli O157:H7 Tq method, when processing samples either using the PPMX or by the manual method. These HT tubes will give greater flexibility to the analyst to process more samples by GDS in a minimal amount of time. Method Recommendations Based on the results of these inclusivity and methods comparison studies, it is recommended that the Assurance GDS for E . coli O157:H7 Tq method be adopted First Action Official Methods SM status for a matrix extension for finely textured beef, carcass cloths and green onions. In addition, the assay should also be adopted for method modifications for 1) use of the Assurance GDS PipetMax® system to process samples and also 2) analysis using the high-throughput (HT) amplification tubes. References

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