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B
ird
et al
.:
J
ournal of
AOAC I
nternational
V
ol
.
100, N
o
.
1, 2017
Evaluation of 3MMolecular Detection Assay (MDA)
2–
Listeria
for the Detection of
Listeria
Species in Select Foods
and Environmental Surfaces: Collaborative Study, First
Action 2016.07
P
atrick
B
ird
, J
onathan
F
lannery
, E
rin
C
rowley
, J
ames
A
gin
,
and
D
avid
G
oins
Q Laboratories, Inc., 1400 Harrison Ave, Cincinnati, OH 45214
L
isa
M
onteroso
3M Food Safety Department, 3M Center, Bldg 260-6B-01, St. Paul, MN 55144
Collaborators: C. Barnes; B. Bastin; D. Baumler; D. Bosco; A. Brandt; R. Brooks; E. Budge; A. Calle; D. Campos; C. Chavarria; C. Diaz Proano;
Z. Geurin; C. Gies; F. Hernandez; D. Isfort; C. Lopez; L. Ma; E. Maranan; Z. Metz; J. Miller; A. Repeck; B. Schindler; M. Shekhawat; E. Sjogren;
R. Smith; C. Timmons; G. Trevino; J. Walia; D. Wood; C. Zook
3M Molecular Detection Assay (MDA) 2–
Listeria
uses loop-mediated isothermal amplification
and bioluminescence detection to rapidly detect
Listeria
species in a broad range of food types and
environmental surfaces. Using an unpaired study
design, MDA 2–
Listeria
was compared with the U.S.
Department of Agriculture, Food Safety and Inspection
Service’s
Microbiology Laboratory Guidebook
Chapter 8.09 “Isolation and identification of
Listeria
monocytogenes
from red meat, poultry and egg
products, and environmental samples” reference
method for the detection of
Listeria
in deli turkey
and raw chicken breast fillet. Technicians from 13
laboratories located within the continental United
States and Canada participated in the collaborative
study. Each matrix was evaluated at three levels of
contamination: uninoculated control (0 CFU/test
portion), low inoculum (0.2–2 CFU/test portion), and
high inoculum (2–5 CFU/test portion). Statistical
analysis was conducted according to the probability
of detection (POD) statistical model. Results
obtained for the low-inoculum-level test portions
produced a difference between two laboratory POD
values (dLPOD) with 95% confidence intervals
of 0.04 (–0.08, 0.17) for deli turkey, indicating the
difference between the methods was not statistically
significant at the
P
= 0.05. For raw chicken breast
fillet, a dLPOD value with 95% confidence interval of
0.16 (0.04, 0.28) indicated a statistically significant
difference between the two methods, with an
observed higher proportion of positive results by the
candidate method than the reference method.
L
isteria,
a hardy Gram-positive, rod-shaped bacterium, is
often found in food-manufacturing facilities, leading to
the contamination of food commodities (1). Due to the
ubiquitous nature of
Listeria
, this organism is used as a hygiene
indicator in all stages of the food-processing chain. Detection
of
Listeria
in production and processing facilities may be an
indicator of unsanitary conditions (2). The organism’s ability
to survive in extreme conditions makes its presence in food a
serious issue. In the past year,
Listeria
has been identified as
the source of several high-profile outbreaks involving bagged
leafy greens and ice cream (3). The 3M Molecular Detection
Assay (MDA) 2–
Listeria
method (3M Food Safety, St. Paul,
MN), using a combination of bioluminescence and isothermal
amplification of nucleic acid sequences, allows for rapid
and specific detection of
Listeria
species in a broad range of
food types and environmental surfaces after 24–32 h of pre-
enrichment. After enrichment, samples are evaluated using
3M MDA 2–
Listeria
on the 3M Molecular Detection System.
Presumptive-positive results are reported in real time, whereas
negative results are displayed after completion of the assay in
approximately 75 min.
Prior to the collaborative study, the 3M MDA 2–
Listeria
method was validated according to AOAC INTERNATIONAL
guidelines (4) in a harmonized AOAC
Performance Tested
Methods
SM
(PTM) study. The objective of the PTM study was to
demonstrate that the 3M MDA 2–
Listeria
method could detect
Listeria
in a broad range of food matrixes and environmental
surfaces as claimed by the manufacturer. For the 3M MDA
2–
Listeria
PTM evaluation, 13 matrixes were evaluated: hot
dogs (25 and 125 g); salmon (25 g); deli turkey (25 and 125 g);
cottage cheese (25 g); vanilla ice cream (25 g); queso fresco
(25 g); spinach (25 g); melon (whole); raw chicken leg pieces
(25 g); raw chicken fillet (25 g); and concrete (sponge, 225 and
100 mL), stainless steel (sponge, 225 mL), and plastic (Enviro
Swab, 10 mL) environmental samples.
Additional PTM parameters (inclusivity, exclusivity,
ruggedness, stability, and lot-to-lot variability) tested in the PTM
studies satisfied the performance requirements for PTM approval.
FOOD BIOLOGICAL CONTAMINANTS
Received July 25, 2016. Accepted by AH August 23, 2016.
This method was approved by the Expert Review Panel for
Microbiology Methods for Food and Environmental Surfaces as First
Action.
The Expert Review Panel for Microbiology Methods for Food and
Environmental Surfaces invites method users to provide feedback on
the First Action methods. Feedback from method users will help verify
that the methods are fit-for-purpose and are critical for gaining global
recognition and acceptance of the methods. Comments can be sent
directly to the corresponding author or
methodfeedback@aoac.org.Corresponding author’s e-mail:
pbird@qlaboratories.comSupplemental information is available on the
J. AOAC Int
. Web site,
http://aoac.publisher.ingentaconnect.com/content/aoac/jaoacDOI: 10.5740/jaoacint.16-0236