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day of testing) and incubated at 42°C for 22-26 hours. An additional 1 mL LB enrichment was added to
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10 mL TT broth and incubated at 35±2°C for 22-26 hours.
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For dry pet food tested with the reference method, 20 spiked and 5 unspiked samples were
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stomached for 2 minutes with approximately 750 mL pre-warmed (35°C) buffered peptone water
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(BPW), then additional pre-warmed media was added to reach a total volume of 3375 mL. Samples
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were incubated at 35±1
o
C for 18-26 hours. After this primary enrichment, 1 mL of each sample was
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added to 9 mL RVS broth. An additional 1 mL of each sample was added to 9 mL TBG broth. All
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secondary enrichments were incubated at 42.5°C for 22-26 hours.
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For dry pet food tested with the BAX® System method, 20 spiked and 5 unspiked samples were
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stomached for 2 minutes with approximately 750 mL pre-warmed (35°C) lactose broth (LB), then
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additional pre-warmed media was added to reach a total volume of 3375 mL. Samples were incubated
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at 35±1°C for 22-26 hours. After this primary enrichment, 10 µL aliquots of each sample were added to
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500 µL brain-heart infusion (BHI) broth and incubated at 37°C for 3 hours. For reference method
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confirmation from the alternative enrichment, 1 mL of each primary enrichment was added to 9 mL
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RVS broth. An additional 1 mL of each sample was added to 9 mL TBG broth. All secondary
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enrichments were incubated at 42.5°C for 22-26 hours.
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BAX® System Method
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All samples were prepared for processing in the BAX® System according to the instructions found
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in the BAX® System User Guide. A rack file was created using the Rack Wizard to enter identifying
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data on the entire rack and on the individual samples. BAX® System lysis reagent was prepared by
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adding 150 µL protease to 12 mL lysis buffer, and 200 µL of prepared lysis reagent was added to each
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cluster (lysis) tube. Sample enrichment was added in 5 µL aliquots to cluster tubes, and all tubes were
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heated at 37ºC for 20 minutes, then at 95ºC for 10 minutes. Lysates were cooled at 2-8°C for at least 5
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minutes, then 30 µL sample lysate was transferred to a PCR tube for the BAX® System real-time
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Salmonella
assay to hydrate the PCR tablet.
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Dupont BAX Salmonella PTM Report
Modification Approved 2012 / PTM Certification No. 081201
For Expert Review Panel Use Only
Do Not Distribute