624-625 / 1195
Table 4.
Comparison of LPT and USDA/FSIS MLG Methods for Detection of
Listeria
in Food – 125g
a
American Type Culture Collection
b
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.
Matrix
Test
Portion
Size
APC
Results
Contaminatio
n Level
MPN/125g
Total
Sample
s
VIDAS LPT
Reference
Method
Chi
Sq.
c
Positive Confirme
d
Deli ham
L.monocytogenes
ATCC
a
7644
125g
60 cfu/g
Uninoculated
NA
5
0
0
0
-
Low
1.31
20
16
16
15
0.14
Ground beef
L.monocytogenes
ATCC 13932
125g
120
cfu/g
Uninoculated
NA
5
0
0
0
-
Low
0.94
20
7
7
7
0
Deli turkey
L.monocytogenes
ATCC 51776
125g
<10
cfu/g
Uninoculated
NA
5
0
0
0
-
Low
0.70
20
11
11
12
0.10