AOAC-RI ERP Book Micro Jan 19 2017

12)Load capped tubes into a clean and decontaminated 3M Molecular Detection Speed Loader Tray. Close and latch the 3M Molecular Detection Speed Loader Tray and lid. 13)Review and confirm the configured run in the 3M Molecular Detection Software. 14)Select the Start button in the software and select the instrument for use. The selected instrument’s lid automatically opens. 15)Place the 3M Molecular Detection Speed Loader Tray into the 3M Molecular Detection Instrument and close the lid to start the assay. Results are provided within 60 minutes, although positives may be detected sooner. 16)All samples must be confirmed from the enrichment broth for the presence of E. coli O157 using appropriate approved reference methods.

Method Comparison Study This study included a method comparison evaluation of the 3M MDA 2 – E. coli O157:H7 compared to the USDA/FSIS-MLG 5.09 Detection, Isolation and Identification of Escherichia coli O157:H7 from Meat Products and Carcass and Environmental Sponges for the detection of E. coli O157:H7 in raw ground beef (73% lean). The food matrix, raw ground beef (72% lean 27% fat), was purchased from a local distributor, prescreened for natural contamination of the target analyte and analyzed for total aerobic count by the FDA/BAM Chapter 3 method [4]. Following the screening, raw ground beef was inoculated with E. coli O157:H7 as indicated in Table A. The method comparison study consisted of evaluating a total of 30 un-paired sample replicates for the matrix. Within each sample set, there were 5 uninoculated samples (0 CFU/test portion), 20 low level inoculated samples (0.2-2 CFU/test portion), and 5 high level inoculated samples (2-5 CFU/test portion). All samples analyzed by the 3M MDA 2 - E. coli O157, regardless of presumptive results, were culturally confirmed by the reference method after10 hours of incubation. Table A: Matrix and Inoculating Organism

Testing Time Point/Incubation Temperature

Reference Method (Enrichment) USDA/FSIS MLG 5.09 (mTSB + CAA)

Matrix/Test Portion Size

Inoculating Organism

# of Replicates

Target Inoculum Level

0 CFU/ Test Portion 0.2-2 CFU/ Test Portion 2-5 CFU/ Test Portion

5

Raw Ground Beef 73% lean (325 gram)

E. coli O157:H7 ATCC 1 43895

10 hours at 41.5°C

20

5

1 ATCC - American Type Culture Collection

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