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Sample Preparation
(a)
Performing Pre-Enrichment:
3M MDA 2 -
E. coli
O157
1)
Raw Ground Beef
A 325 g test portion is aseptically combined with 975 ± 19.5 mL (1 L) of
pre-warmed (41.5 ± 1°C) ISO-BPW in a filtered enrichment bags.
2) Homogenize for 2 ± 0.2 minutes.
3) Incubate at 41.5 ± 1°C for 10 hours.
4) Following incubation, a sample aliquot will be removed to be prepared
by 3M MDA 2 -
E. coli
O157 method.
Lysis Workflow Procedures
(a)
Lysis 3M MDA 2 - E. coli O157 process
1) Allow the lysis solution (LS) tubes to warm to room temperature (20-
25° C) over night (16 – 18 hours). Alternatives to equilibrate the LS
tubes at room temperature are to set the LS tubes on the laboratory
bench for at least 2 hours, incubate the LS tubes in a 37 ± 1°C
incubator for 1 hour or place them in a dry double block heater for 30
seconds at 100° C.
2) Invert the capped tubes to mix. Proceed to the next step within 4
hours.
3) Remove the enrichment broth from the incubator.
4) Use the 3M
™
Molecular Detection Cap/Decap Tool-Lysis to decap one
LS tube strip- one strip at a time.
5) Discard the LS cap.
6) Transfer 20 µL of sample into a LS tube.
7) Repeat step 6 until each individual sample has been added to a
corresponding LS tube in the strip.
8) When all samples have been transferred, transfer 20 µL of Negative
Control (sterile enrichment medium) into a LS tube.
9) Verify that the temperature of the 3M Molecular Detection Heat Block
Insert is at 100 ± 1° C