ERP Micro December 2019

Results for the processing by the PPMX DNA extraction procedure were the same as by manual processing (see Cloth Method Comparison , previous section for recovery). The POD analysis between the GDS EHEC methods presumptive (POD C ) and reference method confirmed (POD R ) results indicated that there was a statistically significant difference at the 5% level for both methods (see Discussion , previous section). Discussion The Assurance® GDS PIPETMAX® (PPMX) is an automated pipetting device for the efficient processing of high-throughput samples. The PPMX machine will robotically capture target organisms from the enrichment using the PickPen TM IMS device and then aliquot directly into the 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 PPMX compared to the GDS EHEC confirmed. Recovery in frozen finely textured beef and carcass cloths was higher in the alternative method compared to the reference method. This is presumably due to the enrichment media as opposed to the sample processing method. These results demonstrate the PPMX machine may be used instead of manual (hand) processing of samples in preparation for PCR analysis. Minor Modifications Study 3 Method modification for alternative tube (HT) format for sample amplification tubes

Results Matrix Studies

No natural contamination was detected in the screening of the product; therefore, the matrix was artificially contaminated with E. coli O157:H7 (see Preparation of Inoculum and Test Portions , above). As per criteria outlined in Appendix J of the Official Methods of Analysis Manual , fractional positive results were obtained for both confirmation methods of the 18 h enrichment for the GDS EHEC

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