950-951 / 1195
Draft
30
Table 13. GovVal Study: Comparison of LMX and Reference methods for Detection of
Listeria monocytogenes
in Foods
a
MPN = Most Probable Number is based on the POD of reference method test portions across labs using the AOAC MPN calculator, with 95% confidence interval
b
N = Number of test portions,
c
Confirmed positive (confirmed results were identical on OAA and L mono chromogenic plates and OA plates)
d
X
2
is defined by Mantel-Haenszel as (n-1)(AF-(B+C+D)E)
2
/(A+B+C+D)(A+E)B+C+D+F)(E+F) where n+A+B+C+D+E+F. A X
2
value greater than 3.84 indicates significance at p>0.05.
e
Relative Sensitivity rate is defined as the total number of confirmed LMX test positive results divided by the total number of reference method positive test results multiplied by 100
Matrix
Strain
MPN
a
/25g
N
b
VIDAS LMX Method
MFHPB-30 Method Chi Square
d
Relative
Sensitivity
e
Presumptive
Pos.
Confirmed
c
Pos.
Positive
Liver paté
L. monocytogenes
1/2a
< 0.075
5
0
0
0
-
-
0.693
20
11
11
10
0.098
110
1.386
20
`15
15
12
1
125
Hot dogs
L. monocytogenes
1/2b
plus 10x
L. innocua
4ab
< 0.075
5
0
0
0
-
-
0.598
20
10
10
8
0.393
125
1.21
20
20
20
13
8.27
154
Raw
fermented
sausage
L. monocytogenes
3b
< 0.075
5
0
0
0
-
-
0.797
20
9
9
10
0.098
90
1.897
20
11
12
10
0.098
120
Sliced
deli turkey
L. monocytogenes
3c
< 0.075
5
0
0
0
-
-
0.598
20
15
15
15
0
100
1.61
20
15
15
17
0.61
88
Sliced
deli ham
L. monocytogenes
4b
< 0.075
5
0
0
0
-
-
1.05
20
10
10
13
0.89
77
1.61
20
16
16
18
0.76
88
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