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A Comparative Evaluation of the 3M
™
Molecular Detection Assay 2 (MDA 2) -
Listeria
for
1
the Detection of
Listeria
species in a Variety of Foods and Environmental Surfaces
2
3
AOAC
Performance Tested Methods
SM
111501
4
5
Abstract
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7
The 3M
™
Molecular Detection Assay 2 (MDA2) -
Listeria
for the detection of
Listeria
species
8
(
L. monocytogenes, L. seeligeri, L. ivanovii, L. innocua, L. grayi, L. welshimeri, L. fleishmanii
9
subsp
.
coloradensis
, L. marthii
,
L. grandensis, L. cornellensis
L. aquatic, L. newyorkensis, L.
10
weihenstephanesis, L. baoriae, L. fleishmanii
subsp. fleishmanii,
L. ivanovii
subsp. londoniensis
11
and
L. riparia)
was evaluated following the 2012 AOAC Research Institute
Performance Tested
12
Methods
SM
program guidelines. The evaluation included inclusivity/exclusivity, lot-to-
13
lot/stability, robustness and matrix studies. The 3M MDA 2 -
Listeria
was compared to various
14
reference methods for raw chicken, bagged raw spinach, cold smoked salmon, deli turkey, whole
15
melons, vanilla ice cream, queso fresco, 4% milk fat cottage cheese, beef hot dogs, stainless
16
steel, sealed concrete and plastic in the matrix study. Twenty replicates of each food matrix were
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analyzed at a low inoculum level of 0.2-2 colony forming units (CFU)/standard test portion, five
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replicates were analyzed at a high level of 2-5 CFU/test portion, and five control replicates were
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analyzed at 0 CFU/standard test portion with the exception of naturally contaminated raw
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chicken (leg pieces) analyzed at the independent laboratory. Naturally contaminated raw chicken
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(leg pieces), analyzed at the independent laboratory, were evaluated using two separate lots
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consisting of twenty replicates for each lot. All environmental surfaces were analyzed using
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twenty replicates at a low inoculum level of ~ 50 CFU/standard area, five replicates were
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analyzed at a high level of ~ 100 CFU/standard area, and five control replicates were analyzed at
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0 CFU/standard test area. Based on the probability of detection statistical model, there were no
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statistically significant differences between the number of presumptive and confirmed positive
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samples or between the candidate and reference method. There were no unexpected results in the
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lot-to-lot/stability, robustness studies. In the inclusivity/exclusivity study, 55 target organisms
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and 30 non-target organisms were tested following the 3M MDA 2 -
Listeria
method with all
30
target organisms detected and none of the non-target organisms detected. The results of this
31
evaluation demonstrate the specificity and sensitivity of the 3M MDA 2 -
Listeria
and its ability
32
to accurately detect
Listeria
species in select food matrixes (beef hot dogs, queso fresco, vanilla
33
ice cream, 4% milk fat cottage cheese, 3% whole milk, bagged raw spinach, cold smoked
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salmon, raw chicken parts, deli turkey, whole cantaloupe) and environmental surfaces (stainless
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steel, sealed concrete, plastic), 24-30 hours post enrichment.
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Authors
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Lisa Monteroso and DeAnn Benesh, 3M Food Safety Division
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Ben Bastin, Jonathan Flannery, Erin Crowley, Patrick Bird, M. Joseph Benzinger, Jr., James
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Agin, David Goins, Q Laboratories, Inc.
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Submitting Company
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3M Company
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Food Safety Department
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3M Center, Bldg. 275-5W-05
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