638-639 / 1195
Table 9 continued.
Probability of Detection Results - VIDAS LPT vs Reference Methods
1
Matrix
Strain
MPN
a
/test portion
N
b
LPT Method
Reference Method
dPOD
C
f
95% CI
g
X
c
POD
C
d
95% CI
x
POD
R
e
95% CI
Peanut butter
-25g-
L. seeligeri
ATCC 35697
control
5
0
0
0.00, 0.43
0
0
0.00, 0.43
0
-0.43, 0.43
1.13
20
15
0.75
0.53-0.88
16
0.80
0.58-0.91
0.05
-0.29, 0.20
Black pepper
-25g-
L. innocua
ATCC 33090
control
5
0
0
0.00, 0.43
0
0
0.00, 0.43
0
-0.43, 0.43
0.79
20
8
0.40
0.21-0.61
10
0.50
0.29-0.70
0.10
-0.37, 0.19
Vanilla ice
cream
-25g-
L. ivanovii
ATCC 13124
control
5
0
0
0.00, 0.43
0
0
0.00, 0.43
0
-0.43, 0.43
1.31
20
18
0.90
0.70-0.97
15
0.75
0.53-0.88
0.15
-0.09, 0.38
Soft cheese
(fresh queso)
-25g-
L. monocytogenes
ATCC 19114
control
5
0
0
0.00, 0.43
0
0
0.00, 0.43
0
-0.43, 0.43
0.79
20
9
0.45
0.26-0.66
11
0.55
0.34-0.74
0.10
-0.37, 0.19
Soft cheese
(fresh queso)
-125g-
L. monocytogenes
ATCC 19114
control
5
0
0
0.00, 0.43
0
0
0.00, 0.43
0
-0.43, 0.43
0.79
20
11
0.55
0.34-0.74
11
0.55
0.34-0.74
0
-0.28, 0.28
Matrix
Strain
Inoculum Level
Added per 100 cm
2
N
b
LPT Method
Reference Method
dPOD
C
f
95% CI
g
X
c
POD
C
d
95% CI
x
POD
R
e
95% CI
Ceramic
L .innocua
SM294 ATCC33090
Control
5
0
0
0.00, 0.43
0
0
0.00, 0.43
0
-0.43, 0.43
1.8 x 10
4
20
6
0.30
0.15, 0.52
3
0.15
0.05, 0.36
0.15
-0.11, 0.39
Stainless steel
L. monocytogenes
Serotype 1
SM 20V ex beef
control
5
0
0
0.00, 0.43
0
0
0.00, 0.43
0
-0.43, 0.43
1.3 x 10
2
20
10
0.50
0.30, 0.70
1
0.05
0.01, 0.24
0.45
0.18, 0.65
Plastic
L.welshimeri
ATCC 35897
control
5
0
0
0.00, 0.43
0
0
0.00, 0.43
0
-0.43, 0.43
1.6 x 10
5
20
18
0.90
0.70, 0.97
15
0.75
0.53, 0.89
0.15
-0.09, 0.38
Concrete
L.monocytogenes
Serotype 4a
SM 295
NCTC11994
control
5
0
0
0.00, 0.43
0
0
0.00, 0.43
0
-0.43, 0.43
8.7 x 10
2
20
14
0.70
0.48, 0.85
15
0.75
0.53, 0.89
0.05
-0.31, 0.22
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
2
b
N = Number of test potions
3
c
x = Number of positive test portions
4
d
POD
C
=
Confirmed candidate method positive outcomes divided by the total number of trials
5
e
POD
R
= Confirmed reference method positive outcomes divided by the total number of trials
6
f
dPOD
C
= Difference between the candidate method and reference method POD values
7
g
95% CI = If the confidence interval of a dPOD does not contain zero, then the difference is statistically significant at the 5% level
8