AOAC-RI ERP Micro June 2016

OMAMAN-30 A/ Collaborative Study Manuscript OMA ERP June 2016 ERP Use Only

Assay(MDA) 2 - Listeria monocytogenes method,usinga combination of bioluminescence and 1 isothermal amplification of nucleic acid sequences,allows for the rapid and specific detection of 2 Listeria monocytogenes in a broad range of food types and environmental surfaces after 24 to 28 3 hoursof pre-enrichment. After enrichment, samples are evaluated using the 3M MDA 2 - 4 Listeria monocytogenes on the 3M ™ Molecular Detection System (MDS). Presumptive positive 5 results are reported in real-time while negative results are displayed after completion of the assay 6 in approximately 75 minutes. 7 Prior to the collaborative study, the 3M MDA 2 - Listeria monocytogenes method was validated 8 according to AOAC Guidelines[4] in a harmonized AOAC ® Performance Tested Method SM 9 (PTM) study. The objective of the PTM study was to demonstrate that the 3M MDA 2- Listeria 10 monocytogenes method could detect Listeria monocytogenes in a broad range of food matrices 11 and environmental surfaces as claimed by the manufacturer. For the 3M MDA 2 - Listeria 12 monocytogenes PTM evaluation, 13 matrices were evaluated:hot dogs (25g & 125g), salmon 13 (25g), deli turkey (25g & 125g), cottage cheese (25g), chocolate milk (25 mL), vanilla ice cream 14 (25g), queso fresco (25g), romaine lettuce (25g), melon (whole), raw chicken leg pieces (25g); 15 concrete (sponge, 225 mL & 100 mL), stainless steel (sponge, 225 mL), and plastic (Enviroswab, 16 10 mL) environmental samples. 17 Additional PTM parameters (inclusivity, exclusivity, ruggedness, stability and lot-to-lot 18 variability) tested in the PTM studies satisfied the performance requirements for PTM approval. 19 The method was awarded PTM certification number 081501 on August 18 th , 2015. 20 The purpose of this collaborative studywas to compare the reproducibility of the 3M MDA 2 - 21 Listeria monocytogenes method to the United States Department of Agriculture (USDA) Food 22 Safety Inspection Service (FSIS) -Microbiology Laboratory Guidebook (MLG)Chapter 8.09 23 Isolation and Identification of Listeria monocytogenes from Red Meat, Poultry and Egg 24 Products, and Environmental Samples [5] for deli turkey (125 g) and raw chicken breast fillet. 29 30 In this collaborative study, two matrices,deli turkeyand raw chicken breast fillet, wereevaluated. 31 The matrices were obtained from a local retailer and screened for the presenceof Listeria 32 monocytogenes by the USDA/FSIS MLG 8.09 reference method . The raw chicken breast fillet 33 was artificially contaminated with fresh unstressed cells of Listeria monocytogenes , American 34 Type Culture Collection (ATCC) 7644, and the deli turkeywas artificially contaminated with 35 heat stressed cells of Listeria monocytogenes ,ATCC 19115,at two inoculation levels: a high 36 inoculation level of approximately 2-5 colony-forming units (CFU)/test portion and a low 37 inoculation level of approximately 0.2-2 CFU/test portion. A set of un-inoculated control test 38 portions (0 CFU/test portion) were also included. 39 Twelve replicate samples from each of the three inoculation levels were analyzed by each 40 method. Two sets of samples (72 total) were sent to each laboratory for analysis by 3M MDA 2 - 41 Listeria monocytogenes and the USDA/FSIS MLG Chapter 8.09 reference method due to the 42 different sample enrichment procedures for each method. Additionally, collaborators were sent a 43 60 g test portion and instructed to conduct atotal aerobic plate count (APC) using 3M ™ 44 Petrifilm™Rapid Aerobic Count Plate (AOAC Official Method 2015.13) [6] on the day samples 45 were received for the purpose of determining the total aerobic microbial load. 46 A detailed collaborative study packet outlining all necessary information related to the study 47 including media preparation, test portion preparation and documentation of results was sent to 48 each collaborating laboratory prior to the initiation of the study. A conference call was then 49 AOAC Research Institute E pert Review Panel Use Only 25 26 27 28 Collaborative Study Study Design

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