AOAC-RI ERP Micro June 2016

OMAMAN-29 A/ Collaboartive Study Manuscript OMA ERP June 2016 ERP Use Only

acid sequences,allows for the rapid and specific detection of Listeria species in a broad range of 1 food types and environmental surfaces after 24 to 28 hoursof pre-enrichment. After enrichment, 2 samples are evaluated using the 3M MDA 2 - Listeria on the 3M ™ Molecular Detection System 3 (MDS). Presumptive positive results are reported in real-time while negative results are 4 displayed after completion of the assay in approximately 75 minutes. 5 Prior to the collaborative study, the 3M MDA 2 - Listeria method was validated according to 6 AOAC Guidelines[4] in a harmonized AOAC ® Performance Tested Method SM (PTM) study. 7 The objective of the PTM study was to demonstrate that the 3M MDA 2- Listeria method could 8 detect Listeria in a broad range of food matrices and environmental surfaces as claimed by the 9 manufacturer. For the 3M MDA 2 - Listeria PTM evaluation, 13 matrices were evaluated:hot 10 dogs (25g & 125g), salmon (25g), deli turkey (25g & 125g), cottage cheese (25g), vanilla ice 11 cream (25g), queso fresco (25g), spinach (25g), melon (whole), raw chicken leg pieces (25g), 12 raw chicken fillet (25g); concrete (sponge, 225 mL & 100 mL), stainless steel (sponge, 225 mL), 13 and plastic (Enviroswab, 10 mL) environmental samples. 14 Additional PTM parameters (inclusivity, exclusivity, ruggedness, stability and lot-to-lot 15 variability) tested in the PTM studies satisfied the performance requirements for PTM approval. 16 The method was awarded PTM certification number 111501 on November 3 rd , 2015. 17 The purpose of this collaborative studywas to compare the reproducibility of the 3M MDA 2 - 18 Listeria method to the United States Department of Agriculture (USDA) Food Safety Inspection 19 Service (FSIS) -Microbiology Laboratory Guidebook (MLG)Chapter 8.09 Isolation and 20 Identification of Listeria monocytogenes from Red Meat, Poultry and Egg Products, and 21 Environmental Samples [5] for deli turkey (125 g) and raw chicken breast fillet. 26 27 In this collaborative study, two matrices,deli turkeyand raw chicken breast fillet, wereevaluated. 28 The matrices were obtained from a local retailer and screened for the presenceof Listeria by the 29 USDA/FSIS MLG 8.09 reference method . The raw chicken breast fillet was artificially 30 contaminated with fresh unstressed cells of Listeria monocytogenes , American Type Culture 31 Collection (ATCC) 7644, and the deli turkeywas artificially contaminated with heat stressed 32 cells of Listeria monocytogenes ,ATCC 19115,at two inoculation levels: a high inoculation level 33 of approximately 2-5 colony-forming units (CFU)/test portion and a low inoculation level of 34 approximately 0.2-2 CFU/test portion. A set of un-inoculated control test portions (0 CFU/test 35 portion) were also included. 36 Twelve replicate samples from each of the three inoculation levels were analyzed by each 37 method. Two sets of samples (72 total) were sent to each laboratory for analysis by 3M MDA 2 - 38 Listeria and the USDA/FSIS MLG Chapter 8.09 reference method due to the different sample 39 enrichment procedures for each method. Additionally, collaborators were sent a 60 g test portion 40 and instructed to conduct atotal aerobic plate count (APC) using 3M ™ Petrifilm™Rapid Aerobic 41 Count Plate (AOAC Official Method 2015.13) [6] on the day samples were received for the 42 purpose of determining the total aerobic microbial load. 43 A detailed collaborative study packet outlining all necessary information related to the study 44 including media preparation, test portion preparation and documentation of results was sent to 45 each collaborating laboratory prior to the initiation of the study. A conference call was then 46 conducted to discuss the details of the collaborative study packet and answer any questions from 47 the participating laboratories. AOAC Research Institute Expert Review Panel Use Only 22 23 24 25 Collaborative Study Study Design

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