552-553 / 1195
1
Table 3. Individual Collaborator Results for Queso Fresco
a
, (25 gram Test Portions)
High-Level Test Portions
Low Level Test Portions
Un-inoculated Test Portions
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 LPT
b
Lab
1
+ +
+
+
+
+
+
+
+
+
+
+
+
+
+
-
-
-
-
+
-
+
-
+
-
-
-
-
-
-
-
-
-
-
-
-
2
+ +
+
+
+
+
+
+
+
+
+
+
+
-
+
-
-
-
-
+
-
-
-
+
-
-
-
-
-
-
-
-
-
-
-
-
3
+ +
+
+
+
+
+
+
+
+
+
+
-
-
+
+
-
+
-
-
-
+
-
-
-
-
-
-
-
-
-
-
-
-
-
-
4
+ +
+
+
+
+
+
+
+
+
+
+
+
-
+
+
+
-
+
-
-
+
+
-
-
-
-
-
-
-
-
-
-
-
-
-
5
+ +
+
+
+
+
+
+
+
+
+
+
+
-
+
-
-
+
+
-
-
-
-
+
-
-
-
-
-
-
-
-
-
-
-
-
6
+ +
+
+
+
+
+
+
+
+
+
+
+
-
-
-
-
+
-
+
+
-
+
+
-
-
-
-
-
-
-
-
-
-
-
-
7
+ +
+
+
+
+
+
+
+
+
+
+
-
-
+
+
-
-
-
+
-
+
+
+
-
-
-
-
-
-
-
-
-
-
-
-
8
+ +
+
+
+
+
+
+
+
+
+
+
+
+
-
+
-
-
+
+
+
+
-
+
-
-
-
-
-
-
-
-
-
-
-
-
9
+ +
+
+
+
+
+
+
+
+
+
+
+
+
-
+
-
+
-
-
+
-
+
+
-
-
-
-
-
-
-
-
-
-
-
-
10
+ +
+
+
+
+
+
+
+
+
+
+
-
-
-
+
+
-
-
+
-
+
+
+
-
-
-
-
-
-
-
-
-
-
-
-
11
e
+ +
+
+
+
+
+
+
+
+
+
+
-
-
-
+
+
-
-
+
-
+
+
+
-
-
-
-
-
-
-
-
-
-
-
-
12
+ +
+
+
+
+
+
+
+
+
+
+
+
-
-
-
+
-
+
+
+
+
+
-
-
-
-
-
-
-
-
-
-
-
-
-
13
+ +
+
+
+
+
+
+
+
+
+
+
-
-
-
+
+
-
+
+
+
-
+
+
-
-
-
-
-
-
-
-
-
-
-
-
14
+ +
+
+
+
+
+
+
+
+
+
+
-
+
-
+
+
-
-
-
+
+
-
d
-
d
-
-
-
-
-
-
-
-
-
-
d
-
-
AOAC 993.12
1
+ +
+
+
+
+
+
+
+
+
+
+
-
+
-
+
+
+
-
-
+
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
2
+ +
+
+
+
+
+
+
+
+
+
+
+
+
+
+
-
+
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
3
+ +
+
+
+
+
+
+
+
+
+
+
+
-
+
+
+
-
-
+
+
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
4
+ +
+
+
+
+
+
+
+
+
+
+
+
+
-
+
+
-
-
-
+
-
+
+
-
-
-
-
-
-
-
-
-
-
-
-
5
+ +
+
+
+
+
+
+
+
+
+
+
+
+
+
-
+
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
6
+ +
+
+
+
+
+
+
+
+
+
+
-
-
-
-
-
+
+
+
+
-
+
+
-
-
-
-
-
-
-
-
-
-
-
-
7
+ +
+
+
+
+
+
+
+
+
+
+
-
-
-
-
+
+
-
+
+
+
+
+
-
-
-
-
-
-
-
-
-
-
-
-
8
+ +
+
+
+
+
+
+
+
+
+
+
-
-
-
-
-
-
+
+
+
+
+
+
-
-
-
-
-
-
-
-
-
-
-
-
9
+ +
+
+
+
+
+
+
+
+
+
+
-
-
-
-
+
+
-
+
+
+
+
+
-
-
-
-
-
-
-
-
-
-
-
-
10 + +
+
+
+
+
+
+
+
+
+
+
-
-
+
+
-
-
+
-
+
-
+
+
-
-
-
-
-
-
-
-
-
-
-
-
11
e
+ +
+
+
+
+
+
+
+
+
+
+
-
+
c
+
+
+
+
-
-
+
-
+
+
+
c
+
c
+
c
-
-
-
+
c
+
c
-
-
+
c
+
c
12 + +
+
+
+
+
+
+
+
+
+
+
+
+
-
+
+
-
-
-
+
-
-
+
-
-
-
-
-
-
-
-
-
-
-
-
13 + +
+
+
+
+
+
+
+
+
+
+
-
-
+
+
+
-
-
-
-
-
+
+
-
-
-
-
-
-
-
-
-
-
-
-
14 + +
+
+
+
+
+
+
+
+
+
+
-
-
-
-
+
-
-
+
+
+
+
+
-
-
-
-
-
-
-
-
-
-
-
-
a
+=
Listeria
spp. were detected in samples; -=
Listeria
spp. were not detected in sample;
b
Confirmed results from OXA and ALOA were identical for each test portion
c
Result reported as
L. grayi
(doubtful API Profile)
d
Sample was presumptive positive on VIDAS LPT but confirmed negative indicating a false positive result
e
Results were not used in statistical analysis
16