ERP Micro December 2019

Validation Study to Demonstrate the Equivalence of a Matrix Extension and Minor Modifications of Assurance® GDS for E . coli O157:H7 Tq Method to the Reference Culture Method Official Methods of Analysis SM Program A NDREW H. L IENAU , SHUQIAO SHEN, M ARKUS T. J UCKER , KHYATI SHAH and LISA JOHN MilliporeSigma, BioControl Systems, Inc. 12822 SE 32 nd St, Bellevue, WA 98005 Abstract Background: The Assurance® GDS for E. coli O157:H7 Tq (GDS EHEC) assay is a test based on a nucleic acid amplification system for the detection of Escherichia coli ( E . coli ) O157:H7. The test utilizes the PickPen TM IMS concentration protocol to concentrate the target organisms from enrichments . It was granted Official Method of Analysis SM status (OMA 2005.04) in 2005. Objective: The OMA validation consisted of a matrix extension for frozen finely textured beef (FTB), carcass cloth and green onions and two method modifications for the use of the automated Assurance® GDS PickPen TM PIPETMAX® (PPMX) system for sample processing and the use of smaller high-throughput (HT) amplification tubes. Methods: The GDS EHEC method was compared to the reference method U. S. Department of Agriculture-Food Safety and Inspection Service Microbiology Laboratory Guidebook (MLG), 5C.00 (2019), and U.S. Food and Drug Administration Bacteriological Analytical Manual (BAM) Chapter 4A (2018) using an unpaired study design. Results: GDS EHEC demonstrated equivalence between presumptive and confirmed results (dPOD CP ) for all matrices including when using either the PPMX sample preparation system or HT amplification tubes. Carcass cloth and frozen FTB recovered significantly more E . coli O157:H7 for the alternative method compared to the reference method (dPOD C ). Conclusions: Results indicated the GDS EHEC method (analyzed by either hand processing or automated PPMX system) can accurately detect the target analyte in FTB, carcass cloth and green onions. Finally, analysis using the HT amplification tubes will give similar results as use of the standard amplification tubes. Introduction to E . coli O157:H7 Escherichia coli ( E . coli ) is a bacterium that lives in human intestines and in the intestines of animals. Most types of E. coli are harmless, but some types can cause illness. A particularly harmful serotype of E. coli , known as E . coli O157:H7, causes bloody diarrhea and can