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3M Molecular Detection Assay Salmonella Collaborative Study
July 2012
OMA-2012-July-XXX
inoculum.
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4.2
Preparation of test portions.
Each food type will be chopped into small pieces
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or divided and a liquid inoculum will be added drop-wise to a bulk quantity of
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food for each inoculation level. The bulk quantity will then be mixed to achieve
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equal distribution of analyte throughout. The test portions will be stored at 2-8
°
C
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for 48-72 h prior to testing.
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4.3
Preparation of 375g wet pet food test portions
involves preparing a sample of
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contaminated matrix so that there is approximately 0.2-2 cfu/375g. A bulk lot of
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wet pet food will be inoculated at 0.2 – 2 cfu/25g. Test portions (25g) will be
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pulled from this bulk lot and randomly assigned to the reference method or the
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3M Molecular Detection Assay
Salmonella
method. An additional 350g
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uncontaminated wet pet food will be added to the 25g test portion assigned to the
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3M Molecular Detection Assay
Salmonella
method resulting in a 375g test
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portion.
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4.4
Shipment of test portions.
Test portions will be packaged in leak-proof,
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insulated containers and shipped (according to the Dangerous Goods Regulations
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IATA for Infections Substances) by overnight carrier to arrive the day before
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initiation of analysis
.
All refrigerated test portions will be packed with ice packs
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to maintain a temperature of <7
°
C during transport. A temperature control sample
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will be included with each shipment to verify temperature of sample upon receipt.
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Upon arrival, the test portions will be stored at 2-8
°
C until they are analyzed.
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4.5
Microbiological analysis.
The test portion preparation is different for the 3M
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Molecular Detection Assay
Salmonella
and reference methods. Therefore, each
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collaborator will receive 60g ground beef and two separate wet pet food test
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portions (25g reference method and 375g 3M Molecular Detection Assay
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Salmonella
method). They will be instructed to test 25g ground beef and 375g
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wet pet food using the 3M 3M Molecular Detection Assay
Salmonella
method
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and 25g wet pet food and 25g ground beef using the appropriate reference
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method. All test portions assayed by the 3M Molecular Detection Assay
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Salmonella
method will be confirmed following the reference method for
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confirmation of
Salmonella
species. The reference method confirmation
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procedures following the appropriate reference methodology (BAM, USDA/FSIS)
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should be performed starting with the secondary enrichment steps. The recovered
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isolates will be identified by the API20E (Official Method 978.24) or the VITEK2
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GN (Official Method 2011.17). The somatic (O) and flagellar (H) tests will also
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be performed.
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One additional control (negative) test portion will be provided to each
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collaborator for each matrix to determine the total plate count on the day of
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analysis.
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DRAFT DOCUMENT
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