16 / 129
B
ird
et al
.:
J
ournal of
AOAC I
nternational
V
ol
.
96, N
o
. 4, 2013
817
(0.31, 1.67) for the low level and 2.19 CFU/test portion (0.94,
5.12) for the high level.
Traditional Confirmation with XLT4 and BGS
For the high level, 130 of 132 test portions were reported as
positive by the VIDAS SPT method, with all portions confirming
positive. For the low level, 58 of 131 test portions were reported
as positive by the VIDAS SPT method with 58 test portions
confirming positive. For the uninoculated controls, none of
the 132 samples produced a presumptive positive result by the
VIDAS SPTmethod, and all confirmed negative. For test portions
analyzed by the USDA/FSIS-MLG method, all of the 132 high
and 57 of 132 low inoculum test portions confirmed positive. For
the uninoculated controls, no test portions confirmed positive.
For the low-level inoculum, dLPOD
C
values of 0.01 (–0.12,
+0.15) were obtained between the USDA/FSIS-MLG method
and the VIDAS SPT method. The confidence intervals obtained
for dLPOD
C
indicated no significant difference between the two
methods. dLPOD
CP
values of 0.00 (–0.15, +0.15) were obtained
Table 3. Individual collaborator results for raw ground beef (25 g test portions) using alternative confirmation
a
High-level test portions
High-level test portions
High-level test portions
Lab 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12
VIDAS SPT (alternative confirmation)
b
1 + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – –
2 + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – –
3 + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – –
4 + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – –
5 + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – –
6 + + + + + + + + + + + + + + + + + + + –
c
+ + + + – – – – – – – – – – – –
7 + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – –
8
d
NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
9 + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – –
10 + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – –
11 + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – –
12
b
+ + + + + + + + + + + + + + + + + + + + + + + + – – –
c
– – – – – – – – –
13 + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – –
14 + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – –
15 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
USDA/FSIS-MLG
1 + + + + + + + + + + + + + – + – + + + – – + – + – – – – – – – – – – – –
2 + + + + + + + + + + + + + + + – – – + + – + – – – – – – – – – – – – – –
3 – + + + + + + + + + + + + + – + + + + + + – – – – – – – – – – – – – – –
4 + + + + + + + + + + + + – + + + + + – + + – + + – – – – – – – – – – – –
5 + + + + + + + + + + + + + + + + + + – + – + + + – – – – – – – – – – – –
6 + + + + + + – + + + + – – – – – + + + + – – + – – – – – – – – – – – – –
7 + + + + + + + + + + + + – + + – – – + – – + – + – – – – – – – – – – – –
8
d
NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
9 + + + + + + + + + + + + + – – + + + + + – + – + – – – – –
b
– – – – – – –
10 – + + + + + + + + + – – + – – – – + + + + + – + – – – – – – – – – – – –
11 + + + + + + + + + + + + + + – + – + + – – + – – – – – – – – – – – – – –
12
d
+ + + + + + + + + + + + – + – + + + – – + – – – – – – – – – – – – – – –
13 + + + + + + + + + + + + – + + – + + – – + + – – – – – – – – – – – – – –
14 + + + + + + + + + + + + + + – + – + – + – – + + – – – – – – – – – – – –
15 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA
a
+= Salmonella spp. were detected in samples; – = Salmonella spp. were not detected in sample; NA = laboratory did not participate in this matrix or
results were not received.
b
Alternative confirmation = direct streak of the primary enrichment onto IBISA and ASAP.
c
Sample was presumptive positive on VIDAS SPT but confirmed negative indicating a false-positive result.
d
Results were not used in statistical analysis due to laboratory error.
e
Sample was confirmed negative on XLT4 and BGS but confirmed positive on ASAP agar.
13