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reagent tubes by soaking in a 1-5% (v:v in water) household bleach solution for 1 hour and away from the assay
1
preparation area.
2
3
RESULTS AND
INTERPRETATION
4
An algorithm interprets the light output curve resulting from the detection of the nucleic acid
5
amplification. Results are analyzed automatically by the software and are color-coded based on the
6
result. A Positive or Negative result is determined by analysis of a number of unique curve parameters.
7
Presumptive positive results are reported in real-time while Negative and Inspect results will be
8
displayed after the run is completed. Presumptive positive results should be confirmed using your
9
preferred method or as specified by local regulations
1,2
.
10
11
NOTE:
Even a negative sample will not give a zero reading as the system and 3M Molecular Assay
Salmonella
12
amplification reagents have a “background” relative light unit (RLU).
13
14
In the rare event of any unusual light output, the algorithm labels this as “Inspect.” 3M recommends
15
the user to repeat the assay for any Inspect samples. If the result continues to be Inspect, proceed to
16
confirmation test using your preferred method or as specified by local regulations.
17
18
Validation Study
19
This study was conducted according to AOAC guidelines
4
outlined in the AOAC General Referee
20
approved harmonized PTM/OMA validation protocol
.
21
22
Inclusivity Testing Methodology
23
Inclusivity testing was conducted to ensure that the 3M Molecular Detection Assay
Salmonella
can
24
detect many different serotypes of
Salmonella
. Pure cultures of 104 different Salmonella serotypes
25
(Table 2 in Appendix) were used to confirm the inclusivity of the test, post complete enrichment of the
26
organisms. Target were cultured overnight in 3M BPW ISO at 37 ± 1
o
C for 18 hours then diluted via
27
ten-fold serial dilutions to a level of less than 10
5
CFU/mL (Colony Forming Unit/mL) prior to evaluation
28
following the 3M Molecular Detection Assay
Salmonella
.
29
30
Exclusivity Testing Methodology
31
Exclusivity testing was conducted to ensure that the 3M Molecular Detection Assay
Salmonella
is
32
specific for the detection of the target organism. Pure cultures of 32 different non-Salmonella
33
serotypes (Table 3 in Appendix) were used to confirm the exclusivity of the test. Organisms were
34
cultured overnight in Tryptic Soy Broth (TSB) at 35 ± 1
o
C for 18 hours then diluted to approximately
35
100 times the limit of detection prior to evaluation following the 3M Molecular Detection Assay
36
Salmonella
.
37
38
Inclusivity/Exclusivity Results
39
Of the 104 cultures tested, only one strain of one serotype,
Salmonella enterica
Westhampton, was
40
shown to be negative by the 3M Molecular Detection Assay Salmonella. It is widely recognized that
41
the
invA
gene is a pathogenicity marker for defining
Salmonella
genus.
5-10
While this strain may be
42
identified as
Salmonella
, it may lack the required pathogenicity gene and would be considered atypical
43
and non-pathogenic. None of the 32 non-
Salmonella
serotypes tested were detected as positive by
44
the 3M Molecular Detection Assay
Salmonella
.
45
46
Ruggedness Testing Methodology
47
10