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Definitions
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a)
Probability of Detection (POD).—
The proportion of positive analytical outcomes for a
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qualitative method for a given matrix at a given analyte level or concentration. POD is
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concentration dependent. Several POD measures can be calculated; POD
R
(reference method
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POD), POD
C
(confirmed candidate method POD), POD
CP
(candidate method presumptive
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result POD) and POD
CC
(candidate method confirmation result POD).
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b)
Difference of Probabilities of Detection (dPOD).—
Difference of probabilities of detection is
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the difference between any two POD values. If the confidence interval of a dPOD does not
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contain zero, then the difference is statistically significant at the 5% level.
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Principle of the Method
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3M™ Molecular Detection Assay 2 -
Listeria
is used with the 3M™ Molecular Detection
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System for the rapid and specific detection of
Listeria
species in enriched food and
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environmental samples.
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The 3M Molecular Detection Assays use loop-mediated isothermal amplification to rapidly
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amplify nucleic acid sequences with high specificity and sensitivity, combined with
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bioluminescence to detect the amplification. Presumptive positive results are reported in real-
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time while negative results are displayed after the assay is completed. Presumptive positive
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results should be confirmed using the laboratory’s preferred method or as specified by local
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regulations.
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General Information
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Listeria
is a small, Gram-positive rod that can be found in soil or carried by animals. Many
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foods have been associated with
Listeria
contamination: uncooked meats, uncooked
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vegetables, cantaloupe, pasteurized and unpasteurized milk, and other dairy and processed
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foods. [5] The resulting illness, listeriosis, from
Listeria monocytogenes
ingestion is rare but
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can be fatal. The disease may appear as meningitis in adults and can affect unborn children
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due to its ability to cross through the placenta.
Listeria
contamination often occurs post-
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cooking, before packaging as
Listeria
can survive longer under adverse environmental
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conditions that can most other vegetative bacteria that present a concern for the food safety
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industry. [6] Manufacturing facilities implement sanitation practices and regular surface
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screening for the presence of
Listeria
on food contact surfaces to monitor their food
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production environments. The regular surface screening for non -
Listeria monocytogenes
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species is used as an indicator to monitor for the risk of
Listeria monocytogenes
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contamination and is typically part of a food manufacturing facility’s Hazard Analysis
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Critical Control Point (HACCP) plan. The 3M MDA 2 -
Listeria
was developed to provide
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rapid and specific detection of
Listeria
in enriched food samples and on food processing
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surfaces.
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Materials and Methods
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