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B
ird
et al
.:
J
ournal of
AOAC I
nternational
V
ol
.
100, N
o
.
2, 2017
chicken breast fillet, a statistically significant differencewas observed
between the reference and candidate methods. The dLPOD
C
,
being significantly greater than 0, showed an observed higher
proportion of positive results by the candidate method compared
to the reference method. One possible contribution for the higher
observed proportion of positive results observed with the 3MMDA
2 –
Listeria monocytogenes
method was the use of DF Broth for
the candidate method. This enrichment media formulation is less
selective than the modified University of Vermont medium used in
theUSDA/FSISMLGreferencemethod andmayhave contributed to
the higher observed proportion positive results during the evaluation.
Asecond possible contribution for the higher observed proportion of
positive results is the length of the primary enrichment. Test portions
evaluated by the 3MMDA2 –
Listeria monocytogenes
method were
incubated for a minimumof 28 h in the primary enrichment, whereas
the USDA/FSIS MLG reference method had a maximum primary
enrichment time of 26 h. No statistically significant difference
was observed between the candidate method’s presumptive and
confirmed results for this matrix.
Recommendations
It is recommended that the 3M MDA 2 –
Listeria
monocytogenes
method be adopted as Official First Action status
for the detection of
L. monocytogenes
in a variety of foods and
on select environmental surfaces, including hot dogs (25 and
125 g), salmon (25 g), deli turkey (25 and 125 g), cottage cheese
(25 g), chocolate milk (25 mL), vanilla ice cream (25 g), queso
Figure 2. (A) LPOD and (B) dLPOD values of candidate method versus reference method for raw chicken breast fillet (25 g).