ERP Micro December 2019

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Introduction

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Assurance® GDS for E . coli O157:H7 Tq

This proposes this protocol is for several combined method comparison studies to demonstrate the equivalence of minor modifications to the Assurance® GDS for E. coli O157:H7 Tq (GDS O157),

AOAC Official Method 2005.04.

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Assurance GDS for E. coli O157:H7 Tq is an automated gene-based assay that uses proprietary probes and specific primers directed against a highly conserved DNA sequence of the target organism. The GDS O157 method detects strains of E. coli O157:H7 and toxigenic Escherichia coli O157:NM (non-motile). The assay is designed to be highly selective, and does not detect microorganisms that are potential cross-reactors in antibody-based assays, including E. coli O157 that are not H7 or NM, and other microorganisms that express O157 antigen but are not E. coli O157:H7. The GDS O157 method also uses a proprietary device and reagents that concentrate populations of target microorganisms, thereby providing increased sensitivity and elimination of potential competitive microflora. The GDS method was adopted AOAC Official Method Final The proposed modifications to the GDS O157 method includes a) the extension for matrices to include frozen finely trimmed beef (FTB, 25 g and 375 g), carcass cloths , fresh vegetables (typegreen onion, 25 g only) and b) the use of an automated system, Assurance® GDS PickPen® PIPETMAX (PPMX), for sample preparation. Raw beef trim will also be analyzed by the PPMX. Action in 2007.

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Results will automatically be interpreted via Assurance GDS for E. coli O157:H7 Tq software

( Attachment 1 ).

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Validation Overview for the Assurance GDS for E . coli O157:H7 Tq

Three method modifications will be performed for GDS O157.

The GDS O157 will be validated according to the AOAC INTERNATIONAL Methods Committee Guidelines for Validation of Microbiological Methods for Food and Environmental Surfaces (1) for specific detection of the E . coli O157:H7 in frozen finely trimmed beef , fresh vegetables and carcass cloths . The reference method s for the matrix studiesfinely trimmed beef and carcass cloth are is the U.S. Department of Agriculture-Food Safety and Inspection Service Microbiology Laboratory Guidebook (MLG), 5.00, 5.09,5C.00, Detection, Isolation and Identification of O157:H7Top Seven Shiga Toxin-Producing Escherichia coli (STECs) from Meat Products and Carcass and Environmental Sponges (2). The reference method for the fresh vegetables is the U.S. Food & Drug Administration Bacteriological Analytical Manual (BAM), Chapter 4A,

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Diarrheagenic Escherichia coli (3).

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