110 / 596
14
For the high inoculum level, 132 out of 132 test portions (POD
CP
of 1.00) were reported as
1
presumptive positive by the 3M MDA 2 –
Listeria
method with 132out of 132 test portions
2
(POD
CC
of 1.00) confirming positive.For samples that produced presumptive positive results on
3
the 3M MDA 2 –
Listeria
method, 132out of 132 samples confirmed positive (POD
C
of 1.00). For
4
test portions evaluated by the USDA/FSISMLG reference method, 132 out of 132 test portions
5
produced positive results. A dLPOD
C
value of 0.00 with 95% confidence intervals of (-0.03,
6
0.03) was obtained between the candidate and reference method, indicating no statistical
7
significant difference between the two methods. A dLPOD
CP
value of 0.00 with 95% confidence
8
intervals of (-0.03, 0.03) was obtained between presumptive and confirmed results indicating no
9
statistically significant difference between the presumptive and confirmed results.
10
For the un-inoculated controls, 0 out of 132 samples (POD
CP
of 0.00) produced a presumptive
11
positive result by the 3M MDA 2 -
Listeria
method with 0out of 132 test portions (POD
CC
of
12
0.00) confirming positive. For samples that produced presumptive positive results on the 3M
13
MDA 2 –
Listeria
method, 0out of 132 samples confirmed positive (POD
C
of 0.00). For test
14
portions evaluated by the USDA/FSIS MLG reference method, 0 out of 132 test portions
15
produced positive results. A dLPOD
C
value of 0.00 with 95% confidence intervals of (-0.03,
16
0.03) was obtained between the candidate and reference method, indicating no statistical
17
significant difference between the two methods. A dLPOD
CP
value of 0.00 with 95% confidence
18
intervals of (-0.03, 0.00) was obtained between presumptive and confirmed results indicating no
19
statistically significant difference between the presumptive and confirmed results.
20
21
Detailed results of the POD statistical analysis are presented in Table 2016.2A and Figures 1A-
22
1B.
23
24
Raw Chicken Breast Fillet (25 g Test Portions)
25
26
Raw chicken breast fillet test portions were inoculated at a low and high inoculum level and were
27
analyzed for the detection of
Listeria
spp. Un-inoculated controls were included in each
28
analysis. Laboratory 11 did not participate in the evaluation of this matrix. Laboratory 10
29
submitted data that indicated cross contamination of the inoculating organism in the un-
30
inoculated control samples. Further analysis at the coordinating laboratory confirmed the cross
31
contamination of the un-inoculated controls. Due to this issue, the data submitted from
32
Laboratory 10 was not used in the statistical analysis. All other laboratories submitted data for
33
both methods evaluated. The MPN levels obtained for this matrix, with 95% confidence
34
intervals, were 0.66 CFU/test portion (0.51, 0.83) for the low level and 6.24 CFU/test portion
35
(3.58, 10.88) for the high level.
36
For the low inoculum level, 88 out of 132 test portions (POD
CP
of 0.67) were reported as
37
presumptive positive by the 3M MDA 2 –
Listeria
method with 86out of 132 test portions
38
(POD
CC
of 0.65) confirming positive. For samples that produced presumptive positive results on
39
the 3M MDA 2 –
Listeria
method, 85out of 132 test portions confirmed positive (POD
C
of 0.64).
40
For test portions evaluated by the USDA/FSIS MLGreference method, 64 out of 132 test
41
portions produced positive results. A dLPOD
C
value of 0.16 with 95% confidence intervals of
42
(0.04, 0.28) was obtained between the candidate and reference method, indicating a statistically
43
AOAC Research Institute
Expert Review Panel Use Only
OMAMAN-29 A/ Collaboartive Study Manuscript
OMA ERP June 2016
ERP Use Only