AOAC RI ERP Final Action Recommendations eBook

Dupont BAX Salmonella PTM Report Modification Approved 2012 / PTM Certification No. 081201 For Expert Review Panel Use Only Do Not Distribute

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Screen prompts were followed to load samples into the cycler/detector and run a full process with

the “Real Time Salmonella” target. At the completion of the PCR and detection process, the screen

prompts were followed to remove samples and display results.

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BAX® System results were displayed as follows:

Indeterminate result

Yellow (?)

Green (-)

Negative for Salmonella

Yellow (?) with red slash

Signal error

Red (+)

Positive for Salmonella

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Reference Methods

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For ground beef, 10 µL of each secondary enrichment for test and reference method samples was

streaked onto XLT-4 and BGS agars (for the USDA-MLG method) or BS and BGS agars (for the HC

Compendium method). All agars were incubated at 35°C for 18-24 hours, after which plates were

examined for colonies with typical characteristics of Salmonella . If typical colonies were not present on

BS plates after 18-24 hours, they were incubated for an additional 22-26 hours and reexamined.

Suspect colonies were confirmed using the biochemical and serological methods described in the

appropriate corresponding reference methods (biochemical, serological) [3,4].

For cream cheese, 10 µL of each TT and RV broth enrichment was streaked onto BS agar, XLD

agar and HE agar. All agars were incubated at 35°C for 22-26 hours, after which plates were

examined for colonies with typical characteristics of Salmonella . Suspect colonies were confirmed

using the biochemical and serological methods described in the FDA-BAM [2].

AOAC INTERNATIONAL For dry pet food, 10 µL of each RVS and TBG broth was streaked onto Bismuth Sulfite (BS) and Brilliant Green Sulfa (BGS) agars. Plates were incubated at 35°C for 22-26 hours. If colonies suggestive of Salmonella had not developed on BS plates, then these plates were incubated for an additional 22-26 hours. Suspect colonies were confirmed using the biochemical and serological

methods described in the Health Canada Compendium of Microbiological Methods [3].

Statistical Analysis

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Statistical analysis was conducted for this study using the Probability of Detection (POD)

statistical treatment of data as described in the current AOAC validation guidelines [5].