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3M MDA 2
Listeria
species and
L. monocytogenes
Collaborative Study
OMA-2016-MONTH-XXX
5/4/16
5.6.6
Transfer 20 µL Negative Control [NC], sterile enrichment medium (e.g.
Demi-Fraser Broth) into a Lysis Solution [LS] tube after all enriched
samples have been completed. Do not use water as a NC.
5.6.7
Place uncovered LS tubes in 3M Molecular detection Heat block, heat
15±1 min at 100±1°C. LS Solution will change from pink (cool) to yellow
(hot).
5.6.8
Place LS tubes (without rack lid) in chill block insert (at ambient
temperature) for 5-10 min. Lysis solution in LS tube will revert to pink
color.
5.6.9
Transfer 20 µL sample lysate from the upper portion of fluid in the LS
tube into regent tube. Mix gently by pipetting up and down 5 times.
5.6.10
Transfer 20 µL of NC lysate into a reagent tube.
5.6.11
Transfer 20 µL of NC lysate into a Reagent Control (RC) tube.
5.6.12
When all samples have been transferred, load capped tubes into speed
loader tray and close lid.
5.6.13
Start assay.
5.6.14
Results and Interpretation - An algorithm interprets the light output curve
resulting from the detection of the nucleic acid amplification. Results are
analyzed automatically by the software and are color-coded based on the
result. A Positive or Negative result is determined by analysis of a number
of unique curve parameters. Presumptive positive results are reported in
real-time while Negative and Inspect results will be displayed after the run
is completed. Presumptive positive results should be confirmed using your
preferred method or as specified by local regulations.
5.6.15
NOTE:
Even a negative sample will not give a zero reading as the
3M MDS and 3M MDA amplification reagents have a “background”
relative light unit (RLU).
In the rare event of any unusual light output, the algorithm labels this
as “Inspect.” 3M recommends the user to repeat the assay for any
Inspect samples. If the result continues to be Inspect, proceed to
confirmation test using your preferred method or as specified by local
regulations.
5.6.16
Confirmation
All positive 3M MDA 2 -
Listeria monocytogenes
results must be
confirmed. Confirmation should be performed using the primary
enrichment, carried through as described in the reference method starting
with the secondary transfer and selective isolation for deli turkey and
selective isolation for raw chicken breast. Confirmation should be
initiated within 72 hrs. Isolate on a selective agar and identify 1 to 5
typical colonies according to the conventional tests described in the
AOAC or USDA/FSIS MLG methods.
AOAC Research Institute
Expert Review Panel Use Only
OMAMAN-29/OMAMAN-30 Combined Collaborative Study Protocol
OMA ERP - June 2016
ERP Use Only