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434
C
rowley
et al
.
:
J
ournal of
AOAC I
nternational
V
ol
. 97, N
o
. 2, 2014
handled observing the usual safety precautions (do
not ingest or inhale).
A. Principle
VIDAS
®
UP
Listeria
(LPT) method is for use on the automated
VIDAS instrument for the detection of
Listeria
antigens using
the enzyme-linked fluorescent assay (ELFA) method. The
assay also incorporates phage proteins allowing an increase in
sensitivity and specificity compared to traditional immunoassay.
The Solid Phase Receptacle (SPR
®
) serves as the solid phase as
well as the pipetting device. The interior of the SPR is coated
with proteins specific for
Listeria
receptors. Reagents for the
assay are ready-to-use and predispensed in the sealed reagent
Table 2013.10A. Summary of results for the detection of
Listeria
spp. in queso fresco (25 g)
Method
a
VIDAS LPT w/OXA
VIDAS LPT w/ALOA
Inoculation level
Uninoculated
Low
High Uninoculated
Low
High
Candidate presumptive positive/total No. samples
analyzed
1/156
80/156
156/156
1/156
80/156
156/156
Candidate presumptive POD (CP)
0.01
0.51
1.00
0.01
0.51
1.00
(0.01, 0.04)
(0.43, 0.59)
(0.98, 1.00)
(0.01, 0.04) (0.43, 0.59)
(0.98, 1.00)
s
r
b
0.08
0.51
0.00
0.08
0.51
0.00
(0.07, 0.15)
(0.46, 0.52)
(0.00, 0.15)
(0.07, 0.15) (0.46, 0.52)
(0.00, 0.15)
s
L
c
0.00
0.00
0.00
0.00
0.00
0.00
(0.00, 0.03)
(0.00, 0.13)
(0.00, 0.15)
(0.00, 0.03) (0.00, 0.13)
(0.00, 0.15)
s
R
d
0.08
0.51
0.00
0.08
0.51
0.00
(0.07, 0.13)
(0.46, 0.52)
(0.00, 0.21)
(0.07, 0.13) (0.46, 0.52)
(0.00, 0.21)
P
value
e
0.4395
0.9210
1.0000
0.4395
0.9210
1.0000
Candidate confirmed positive/total No. samples analyzed 0/156
78/156
156/156
0/156
78/156
156/156
Candidate confirmed POD (CC)
0.00
0.50
1.00
0.00
0.50
1.00
(0.00, 0.02)
(0.42, 0.58)
(0.98, 1.00)
(0.00, 0.02) (0.42, 0.58)
(0.98, 1.00)
s
r
0.00
0.51
0.00
0.00
0.51
0.00
(0.00, 0.15)
(0.46, 0.52)
(0.00, 0.15)
(0.00, 0.15) (0.46, 0.52)
(0.00, 0.15)
s
L
0.00
0.00
0.00
0.00
0.00
0.00
(0.00, 0.15)
(0.00, 0.14)
(0.00, 0.15)
(0.00, 0.15) (0.00, 0.14)
(0.00, 0.15)
s
R
0.00
0.51
0.00
0.00
0.51
0.00
(0.00, 0.21)
(0.46, 0.52)
(0.00, 0.21)
(0.00, 0.21) (0.46, 0.52)
(0.00, 0.21)
P
value
1.0000
0.9161
1.0000
1.0000
0.9161
1.0000
Positive reference samples/total No. samples analyzed
0/156
76/156
156/156
0/156
76/156
156/156
Reference POD
0.00
0.49
1.00
0.00
0.49
1.00
(0.00, 0.02)
(0.41, 0.57)
(0.98, 1.00)
(0.00, 0.02) (0.41, 0.57)
(0.98, 1.00)
s
r
0.00
0.52
0.00
0.00
0.52
0.00
(0.00, 0.15)
(0.46, 0.52)
(0.00, 0.15)
(0.00, 0.15) (0.46, 0.52)
(0.00, 0.15)
s
L
0.00
0.00
0.00
0.00
0.00
0.00
(0.00, 0.15)
(0.00, 0.10)
(0.00, 0.15)
(0.00, 0.15) (0.00, 0.10)
(0.00, 0.15)
s
R
0.00
0.52
0.00
0.00
0.52
0.00
(0.00, 0.21)
(0.47, 0.52)
(0.00, 0.21)
(0.00, 0.21) (0.47, 0.52)
(0.00, 0.21)
P
value
1.0000
0.9937
1.0000
1.0000
0.9937
1.0000
dLPOD (candidate vs reference)
0.00
0.01
0.00
0.00
0.01
0.00
(–0.02, 0.02) (–0.10, 0.13)
(–0.02, 0.02) (–0.02, 0.02) (–0.10, 0.13) (–0.02, 0.02)
dLPOD (candidate presumptive vs candidate confirmed)
0.01
0.01
0.00
0.01
0.01
0.00
(–0.02, 0.04) (–0.10, 0.13)
(–0.02, 0.02) (–0.02, 0.04) (–0.10, 0.13) (–0.02, 0.02)
a
Results include 95% confidence intervals.
b
Repeatability standard deviation.
c
Among-laboratory standard deviation.
d
Reproducibility standard deviation.
e
P
value = Homogeneity test of laboratory PODs.
Candidates for 2016 Method of the Year
335