3M E. coli O157 Gebrauchsanweisungen Seite 9

10. After the assay is complete, remove the 3M Molecular Detection Speed Loader Tray from the 3M Molecular Detection
Instrument and dispose of the tubes by soaking in a 1-5% (v:v in water) household bleach solution for 1 hour and away
from the assay preparation area.
NOTICE: To minimize the risk of false positives due to cross-contamination, never open reagent tubes containing
amplified DNA. This includes 3M Reagent Control, 3M Molecular Detection Assay 2 - E. coli O157 (including H7)
Reagent Tube, and 3M Matrix Control Tubes. Always dispose of sealed reagent tubes by soaking in a 1-5% (v:v in
water) household bleach solution for 1 hour and away from the assay preparation area.
Results and Interpretation
An algorithm interprets the light output curve resulting from the detection of the nucleic acid amplification. Results are
analysed 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 samples should be confirmed as per the laboratory standard operating procedures or by following
the appropriate reference method confirmation
secondary enrichment broth(s), followed by subsequent plating and confirmation of isolates using appropriate biochemical
and serological methods.
NOTE: Even a negative sample will not give a zero reading as the system and 3M Molecular Detection Assay 2 - E. coli
O157 (including H7) amplification reagents have a "background" relative light unit (RLU) reading.
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.
In the event of discordant results (presumptive positive with the 3M Molecular Detection Assay 2 - E. coli O157
(including H7), non-confirmed by one of the means described above, and in particular for the latex agglutination test),
the laboratory must follow the necessary steps to ensure the validity of the results obtained.
Confirmation of Results According to the NF VALIDATION Certified Method
In the context of the NF VALIDATION, all samples identified as positive by the 3M Molecular Detection Assay 2 - E. coli
O157 (including H7) must be confirmed by one of the following tests:
Option 1: Using the ISO 16654
Option 2: Implementing a confirmation method consisting of the following: Streak 50 μL of the buffered peptone water
enrichment onto a Cefixime Potassium Tellurite Sorbitol MacConkey (CT-SMAC)
37°C. Streak characteristic colonies onto nutrient agar and perform latex agglutination test directly onto isolated colonies.
If the 3M Molecular Detection Assay 2 - E. coli O157 (including H7) results are not confirmed, perform an immunomagnetic
separation step and then streak 50 μL onto CT-SMAC.
Option 3: Using nucleic acid probes as described in the EN ISO 7218
or not) from CT-SMAC (see Options 1 or 2). The nucleic acid probes must be different from those used in the 3M Molecular
Detection Assay 2 - E. coli O157 (including H7).
Option 4: Using any other method certified NF VALIDATION, the principle of which must be different from 3M Molecular
Detection Assay 2 - E. coli O157(including H7). The complete protocol described for this second validated method must be
used. All steps prior to the start of confirmation must be common to both methods.
In the event of discordant results (presumptive positive with the alternative method, non-confirmed by one of the means
described above) the laboratory must follow the necessary steps to ensure the validity of the result obtained.
If you have questions about specific applications or procedures, please visit our website at www.3M.com/foodsafety or
contact your local 3M representative or distributor.
Appendix A. Protocol Interruption: Storage and re-testing of samples
1. To store a heat-treated lysate, re-cap the lysis tube with a clean cap (see Lysis section, 4.5)
2. To store an enriched sample, incubate for a minimum of 18 hours prior to storage.
3. Store at 4 to 8°C for up to 72 hours.
4. Prepare a stored sample for amplification by inverting 2-3 times to mix.
5. Decap the tubes.
6. Place the mixed lysate tubes on 3M Molecular Detection Heat Block Insert and heat at 100 ± 1°C for 5 ± 1 minutes.
7. Remove the rack of 3M Lysis Solution tubes from the heating block and allow to cool in the 3M Molecular Detection
Chill Block Insert at least 5 minutes and a maximum of 10 minutes.
8. Continue the protocol at the Amplification section detailed above.
, beginning with transfer from the primary BPW ISO enrichment to
(1,2,3)
standard starting from the buffered peptone water
(3)
enrichment.
(3)
agar plate. Incubate for 24 ±3 hours at
(3)
standard, performed on isolated colonies (purified
(5)
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(English)
(3)