229 / 596
15
presumptive and confirmed results indicating no statistically significant difference between the
1
presumptive and confirmed results.
2
For the high inoculum level, 129 out of 132 test portions (POD
CP
of 0.98) were reported as
3
presumptive positive by the 3M MDA 2 –
Listeria monocytogenes
method with 132out of 132
4
test portions (POD
CC
of 1.00) confirming positive. For samples that produced presumptive
5
positive results on the 3M MDA 2 –
Listeria monocytogenes
method, 129out of 132 samples
6
confirmed positive (POD
C
of 0.98). For test portions evaluated by the USDA/FSIS-MLG
7
reference method, 132 out of 132 test portions produced positive results. A dLPOD
C
value of
8
-0.02 with 95% confidence intervals of (-0.06, 0.01) was obtained between the candidate and
9
reference method, indicating no statistically significant difference between the two methods. A
10
dLPOD
CP
value of -0.02 with 95% confidence intervals of (-0.06, 0.01) was obtained between
11
presumptive and confirmed results indicating no statistically significant difference between the
12
presumptive and confirmed results.
13
For the un-inoculated controls, 0 out of 132 samples (POD
CP
of 0.00) produced a presumptive
14
positive result by the 3M MDA 2 -
Listeria monocytogenes
method with 0 out of 132 test
15
portions (POD
CC
of 0.00) confirming positive. For samples that produced presumptive positive
16
results on the 3M MDA 2 –
Listeria monocytogenes
method, 0 out of 132 samples confirmed
17
positive (POD
C
of 0.00). For test portions evaluated by the USDA/FSIS MLG reference method,
18
0 out of 132 test portions produced positive results. A dLPOD
C
value of 0.00 with 95%
19
confidence intervals of (-0.03, 0.03) was obtained between the candidate and reference method,
20
indicating no statistical significant difference between the two methods. A dLPOD
CP
value of
21
0.00 with 95% confidence intervals of (-0.03, 0.00) was obtained between presumptive and
22
confirmed results indicating no statistically significant difference between the presumptive and
23
confirmed results.
24
25
Detailed results of the POD statistical analysis are presented in Table 2016.2B and Figures 1C-
26
1D.
27
28
29
Discussion
30
31
No negative feedback was provided by the collaborating laboratories in regard to the
32
performance of the 3M MDA 2-
Listeria monocytogenes
method. For the raw chicken breast
33
fillet, Laboratory 10 reported isolating
Listeria monocytogenes
from two un-inoculated control
34
samples. The isolates were sent for further identification and it was determined that they were
35
the same strain as the inoculating organism, indicating that cross contamination of the sample
36
occurred. Due to the fact that cross contamination occurred, just cause for removal of the data
37
was established and the data generated by Laboratory 10 was therefore not included in the
38
statistical analysis.
39
Overall, the data generated during this evaluation demonstrates the reproducibility of this new
40
method. For the deli turkey analysis, the POD statistical analysis indicated thatno statistically
41
significant difference between the candidate method and the reference method or between the
42
presumptive and confirmed results of the candidate method was obtained. For raw chicken
43
AOAC Researc Institute
Expert Review Panel Use Only
OMAMAN-30 A/ Collaborative Study Manuscript
OMA ERP June 2016
ERP Use Only