351 / 596
13
In the rare event of any unusual light output, the algorithm labels this as “Inspect.” 3M
1
recommends the user to repeat the assay for any Inspect samples. If the result continues to be
2
Inspect, proceed to confirmation test using your preferred method or as specified by local
3
regulations.
4
5
Results of Collaborative Study
6
7
For this collaborative study, the 3M Molecular Detection Assay (MDA) 2 -
Listeria
method was
8
compared to the USDA FSIS MLG 8.09 reference method for deli turkey and raw chicken breast
9
fillet. A total of 13 laboratories throughout the United Statesand Canada participated in this
10
study, with 11 laboratories submitting data for the deli turkey and 12 laboratories submitting data
11
for the raw chicken breast fillet. See Table 1 for a summary of laboratory participation for each
12
matrix. Each laboratory analyzed 36 test portions for each method per matrix: 12 inoculated
13
with a high level of
Listeria
, 12 inoculated with a low level of
Listeria
, and 12 un-inoculated
14
controls.
15
A background screen of the matrix indicated an absence of indigenous
Listeria
species in both
16
matrices.Ten (10) replicate test portions (randomly sampled from 50% of the total packages used
17
in the analysis) were screened for the presence of
Listeria
species. All test portions produced
18
negative results for the target analyte.
19
Results for the heat stress analysis of the inoculum for the deli turkey are presented in Table 2.
20
The raw chicken breast fillet is not heat treated, therefore it was not necessary to injure the
21
cells.
Table 2016.1A and 2016.1B summarize the inter-laboratory results for all foods tested,
22
including POD statistical
analysis.Asper criteria outlined in Appendix J of the AOAC Validation
23
Guidelines, fractional positive results were obtained.Detailed results for each laboratory are
24
presented in Tables 2016.2A and 2016.2B. For each matrix, the level of
Listeria
was determined
25
by MPN on the day of initiation of analysis by the coordinating laboratory. MPN results are
26
presented in Tables 2016.2A and 2016.2B.The individual laboratory and sample results are
27
presented in Tables 1-2 of the Supplementary Materials. The APCresults for each collaborating
28
are presented in Table
53
of the Supplementary Materials.
29
30
Deli Turkey (125 g Test Portions)
31
32
Deli turkeytest portions were inoculated at a low and high level and were analyzed for the
33
detection of
Listeria
spp. Un-inoculated controls were included in each analysis. Laboratories 8
34
and 10 received test portions but were unable to conduct the analysis and therefore no data was
35
submitted. All other laboratories submitted data for both methods evaluated. The MPN levels
36
obtained for this matrix, with 95% confidence intervals, were 0.63 CFU/test portion (0.49,0.80)
37
for the low inoculum level and 4.52 CFU/test portion (3.19, 6.42) for the high inoculum level.
38
For the low inoculum level, 68 out of 132 test portions (POD
CP
of 0.52) were reported as
39
presumptive positive by the 3M MDA 2 –
Listeria
method with 66out of 132 test portions
40
(POD
CC
of 0.50) confirming positive. For samples that produced presumptive positive results on
41
the 3M MDA 2 –
Listeria
method, 66out of 132 samples confirmed positive (POD
C
of 0.50). For
42