553 / 596
portions, there were 0 presumptive positives out of 5 replicates. See Table 17 for robustness
1
results.
2
3
Independent Laboratory Observations
4
5
The results of this study demonstrate the ability of the MDA2
-
Listeria monocytogenes
to detect
6
the presence of
Listeria monocytogenes
in various food matrices and select environmental
7
surfaces after 24-28 hours of a primary enrichment. The MDA2
-
Listeria monocytogenes
offers
8
the benefits of extremely high sensitivity and high specificity for the detection of
Listeria
9
monocytogenes
while reducing the overall time to presumptive results. The MDA2
-
Listeria
10
monocytogenes
also reduces the total analyst time required to obtain final results by
11
implementing a single heat lysis step and cool step, followed up by a single transfer to molecular
12
reaction tubes.The small foot print of the Molecular Detection System requires only minimal lab
13
and bench space, making it easy to move the instrument or pair up additional MDS units to
14
perform multiple MDA runs concurrently. The updated software is user friendly with easy to
15
interpret results. The ability to examine Relative Light Unit (RLU) curves makes trouble
16
shooting more streamlined if any problems occur while testing is being conducted.
17
18
Discussion
19
20
There were no differences between the 24- and 26-hour enrichment time points for the
21
environmental surfaces tested, therefore a 24-hour minimum enrichment will be recommended
22
for these matrices.
23
24
Conclusion
25
26
The 3M MDA2 -
Listeria monocytogenes
AOAC PTM validation study included an
27
inclusivity/exclusivity, lot-to-lot/stability, robustness and matrix studies. The 3M MDA2 –
28
Listeriamonocytogenes
was compared to the USDA/FSIS-MLG 8.09, the FDA-BAM
29
Chapter 10, the AOAC 993.12 or the ISO 11290-1/A1 reference methods for the detection
30
of
Listeriamonocytogenes
. There were nosignificant differences between the 3M MDA2 -
31
Listeriamonocytogenes
method and the corresponding reference method for any of the
32
matrices evaluated. The 3M MDA2 -
Listeria monocytogenes
demonstrated reliability as a
33
rapid and sensitive method for the detection of
Listeria monocytogenes
for the following
34
matrices: beef hot dogs (25 g), deli turkey (125 g), queso fresco (25 g), vanilla ice cream (25
35
g), 4% milk fat cottage cheese (25 g), 3% chocolate whole milk (25 mL), whole melon,
36
romaine lettuce (25 g), bagged raw spinach (25 g), cold smoked salmon (25 g), raw chicken
37
leg pieces (25 g), sealed concrete (sponge enriched in 100mL), plastic (Enviro
sS
wab
38
enriched in 10 mL), stainless steel (sponge enriched in 225 mL).
39
40
References
41
42
1.
Food and Drug Administration Bacteriological Analytical Manual Chapter 10:
Detection and
43
Enumeration of Listeria monocytogenes in Foods
. February, 2013. (Accessed January 2015)
44
45
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