Microbiology Methods for ERP Review 3-2020

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GENE ‐ UP ® SLM 2 Collaborative Study

July 2019

Table 1. Overview of Study Design

# Test Portions (per method)

Inoculating organism

Target Inoculum Levels

Test Portion Codes

Reference Method

Matrix

0 cfu/test portion

12

Raw Ground Beef (80% lean) 375g

Salmonella Bareilly

Random number between 1 ‐ 600

MLG 4.10

0.7 cfu/test portion

12

2 cfu/test portion

12

c) Study Schedule  ‐ The organizing laboratory will prepare test portions and ship at refrigerated temperature (2 ‐ 8 o C) via overnight courier to the collaborators to arrive the week before testing. Test portion processing and analysis will begin the following Monday. Data forms will be completed and faxed or emailed back to the co ‐ Study Directors within 7 days of completion of testing. 4) Test Portion Preparation a) Raw ground beef will be obtained from local retail outlets and screened for the presence of Salmonella. Naturally contaminated test portions will be used if available at sufficient levels. Alternatively, the test portions will be artificially inoculated to meet the target contamination levels of 0.7 cfu/test portion for the low inoculum and 2 cfu/test portion for the high inoculum. b) Preparation of test portions . A liquid inoculum will be added to a bulk quantity of raw ground beef for each inoculation level: 0.7 cfu/test portion and 2 cfu/test portion. The bulk quantity will be mixed to achieve equal distribution of analyte throughout. Test portions (25g) will be pulled from this bulk lot and randomly assigned to the reference method or the candidate method. For the candidate method, an additional 350g uncontaminated raw ground beef will be added to the 25g inoculated test portion resulting in a 375g test portion. The test portions will be stored at 2 ‐ 8 o C for up to 96 h prior to testing. c) Shipment of test portions. Test portions will be packaged in leak ‐ proof, insulated containers and shipped (according to the Dangerous Goods Regulations IATA for Infections Substances) by overnight carrier to arrive the week before initiation of analysis . Test portions will be shipped at refrigerated temperature (2 ‐ 8 o C) during transport. A temperature control sample or temperature probe will be included with each shipment to verify temperature of sample upon receipt. Upon arrival, the test portions will be stored at refrigerated temperature (2 ‐ 8 o C) until they are analyzed. One additional control (non ‐ inoculated) test portion will be provided to each collaborator for each matrix to determine the total plate count on the day of analysis. d) Microbiological analysis. Due to different primary enrichment incubation temperatures, each collaborator will receive a separate set of test portions for each method. They will be instructed to test 375 g test portions using the GENE ‐ UP SLM 2 method and 25 g test portions using the MLG reference method. For both methods, the confirmation procedures will be performed starting with the secondary enrichment steps. Additionally, the candidate method will be validated with an alternative confirmation by directly streaking the primary enrichment onto

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