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Reviewer 9 (McMahon):
N/A
b.
General comments about the method:
Reviewer 1 (Achen):
The method is simple and straightforward and can be used in a food microbiology
laboratory with appropriate training. The use of lyophilized PCR reagents simplifies the
execution of real time PCR and thereby reduces the risk of DNA cross contamination
Reviewer 2 (Douey):
While recommended for the 24 matrices validated during the PTM and pre-collaborative
study, individiual conditions for each matrice, time of incubation, temperature, media used
etc. are not specified.
Introduction
- states most rapid methods need 2 days of enrichment, then by contrast, BAX needs only
90 minutes post enrichment. This isn't a contrast. A contrast would be how long BAX
needs for enrichment compared to other rapid methods. Comparing apples (time of
enrichment) with oranges (time to do the screen test after enrichment).
Test Sample Inoculation and Distribution
- frankfurter samples were inoculated with stressed cells, as is appropriate for processed
foods. Orange juice was inoculated with non-stressed cells (I would consider orange juice a
processed food and the cells should have been stressed). In the pre-collaborative it was
stated they used stressed cells for all processed foods. A list of all food matrices from the
pre-collaborative that were inoculated with stressed cells should be provided, as definitions
may differ as to what is considered a process food.
- states at 5-tube, 3-level MPN estimation of contamination levels was conducted using the
appropriate reference method. Then states that the Least Cost formulations was used to
determine MPN values. Which MPN value was used in the data table? Or does the actual
MPN value somehow get used in the Least Cost formulations spreadsheet? Sorry - I have
never used the Least Cost formulations to determine MPN values.
Reviewer 3 (Hitchins):
The method detects salmonellae in enrichment cultures of food products and processing
surfaces by RT-PCR. PCR reagents are provided in convenient dry tablet form. The
automated BAX System method uses fluorescent detection to analyze PCR product. The PCR
primer for each target (one Salmonella-specific target and one internal control) contains a
fluorescent dye moiety (a different dye for each target) and a quencher moiety. Quecnching
of fluorescence decreases when the primer is incorporated into a target amplicon. The
method specifically detects salmonella (over 100 serotypes tested in preliminary studies). It
failed to detect 30 non-Salmonella relatives in preliminary studies.
Reviewer 4 (Brodsky):
A reliable screening method for Salmonella in a variety of foods.