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980 Bird et al.: Journal of aoaC international Vol . 99, n o. 4, 2016
FOOD BIOLOGICAL CONTAMINANTS
Evaluation of the 3M™Molecular Detection Assay (MDA)
2 – Salmonella for the Detection of Salmonella spp. in Select
Foods and Environmental Surfaces: Collaborative Study,
First Action 2016.01
Patrick Bird , Jonathan Flannery , e rin crowley, James r. agin, and d avid goins
Q Laboratories, Inc., 1400 Harrison Ave, Cincinnati, OH 45214
lisa monteroso
3M Food Safety Department, 3M Center, Bldg 260-6B-01, St. Paul, MN 55144
Collaborators: C. Barnes; B. Bastin; J. Blumfield; T. Bonilla; R. Brooks; E. Budge; A. Calle; D. Campos; J. Casimir; N. Cuthbert;
A. Deshields; Z. Geurin; C. Gies; A. Hankins; L. Hardrath; B. Kupski; M. Mendres; J. Miller; K. Naylor; J. Pickett; A. Repeck;
J. Reynolds; B. Schindler; J. Schoeni; M. Tillottson; L. Thompson; H. Wright; C. Zook
The 3M™ Molecular Detection Assay (MDA)
2 – Salmonella uses real-time isothermal
technology for the rapid and accurate detection
of Salmonella spp. from enriched select food,
feed, and food-process environmental samples.
The 3M MDA 2 – Salmonella was evaluated in
a multilaboratory collaborative study using an
unpaired study design. The 3M MDA
2 – Salmonella was compared to the U.S. Food
and Drug Administration Bacteriological Analytical
Manual Chapter 5 reference method for the
detection of Salmonella in creamy peanut butter,
and to the U.S. Department of Agriculture, Food
Safety and Inspection Service Microbiology
Laboratory Guidebook Chapter 4.08 reference
method “Isolation and Identification of Salmonella
from Meat, Poultry, Pasteurized Egg and Catfish
Products and Carcass and Environmental
Samples” for the detection of Salmonella in raw
ground beef (73% lean). Technicians from
16 laboratories located within the continental
United States participated. Each matrix was
evaluated at three levels of contamination: an
uninoculated control level (0 CFU/test portion),
a low inoculum level (0.2–2 CFU/test portion),
and a high inoculum level (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 difference in collaborator POD
values of 0.03 (95% confidence interval, −0.10 to
0.16) for raw ground beef and 0.06 (95% confidence
interval, −0.06 to 0.18) for creamy peanut butter,
indicating no statistically significant difference
between the candidate and reference methods.
S almonella is a nonspore-forming, rod-shaped,
Gram-negative bacterium that can cause disease in
humans (1). Most of the Salmonella serovars cause
gastrointestinal illness, with annual estimates of over 1 million
illnesses and 450 deaths in the United States (1). A few serovars,
Salmonella Typhi and Salmonella Paratyphi A, B, and C, can
cause typhoidal illness also known as enteric fever (2). In the
past year, Salmonella has been identified as the source of over
20 food-related outbreaks in the United States (3, 4). The 3M™
Molecular Detection Assay (MDA) 2 – Salmonella method uses
a combination of bioluminescence and isothermal amplification
of nucleic acid sequences to rapidly detect Salmonella in select
food matrixes and from environmental surfaces. The isothermal
amplification is a molecular reaction conducted at a constant
temperature, eliminating the need for temperature cycling and
decreasing the time to results.
The 3M MDA 2 – Salmonella method allows for the rapid
and specific detection of Salmonella spp. in select matrixes after
as little as 10 to 18 h of preenrichment using an International
Organization for Standardization (ISO) formulation of buffered
peptone water (BPW; 5). After enrichment, samples are
evaluated using the 3MMDA2 – Salmonella on the 3MMolecular
Detection System (MDS). Presumptive positive results are
reported in real time, whereas negative results are displayed after
completion of the assay in approximately 60 min.
Before the collaborative study, the 3M MDA 2 – Salmonella
method was validated according to AOAC INTERNATIONAL
guidelines (6) in a harmonized AOAC Performance Tested
MethodSM (PTM) study. The objective of the PTM study was
to demonstrate that the 3M MDA 2 – Salmonella method could
detect Salmonella in select food matrixes and environmental
surfaces as claimed by the manufacturer. For the 3M MDA
2 – Salmonella PTM evaluation, 18 matrixes were evaluated:
raw ground beef (73% lean; 25 and 325 g), raw ground chicken
(25 and 325 g), chicken carcass rinse, chicken carcass sponge,
Submitted for publication March 25, 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
Corresponding author’s e-mail:
DOI: 10.5740/jaoacint.16-0085