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1
2
•
Biochemically confirmed positive results:
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Colonies that are green to blue, blue to dark blue, or black or have a blue precipitate around them are
4
biochemically confirmed positive for
Salmonella
species.
5
6
•
Biochemically confirmed negative results:
7
Colonies that remain the same red, dark red or brown color without a blue precipitate are negative for
8
Salmonella
species.
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6.
Colonies may be subcultured for further identification. When subculturing, wear appropriate protective
11
apparel and follow standard good laboratory safety practices (GLP)
2
.
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a.
With a gloved hand, lift the top film and aseptically remove the colony either from the gel or the 3M
13
Petrifilm SALX Confirmation Disk. If a 3M Petrifilm SALX Confirmation Disk is covering the gel,
14
aseptically peel the disk away and then aseptically remove the colony from the gel.
15
b.
Streak the colony onto/into media per appropriate reference method
5,6,7
.
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NOTE:
If the colonies cannot be subcultured within 1 hour of plate removal from the incubator, then
17
store the 3M Petrifilm SALX Plates for later analysis by placing in a sealed plastic bag at -20 to -10°C for
18
no longer than 72 hours in the dark. Allow 3M Petrifilm SALX Plates to warm to room temperature (20-
19
25°C / <60% RH) before continuing subculturing for identification.
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7.
After the test is complete, dispose of the 3M Petrifilm SALX Plates and 3M Petrifilm SALX Confirmation
21
Disks in accordance with current industry standards and/or local regulations.
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Validation Study
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This study was conducted according to AOAC guidelines outlined in the AOAC General Referee approved
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harmonized PTM/OMA validation protocol, “Validation Outline for 3M™ Petrifilm™
Salmonella
Express
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System.”
32
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Inclusivity Testing Methodology
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Inclusivity testing was conducted to ensure that the 3M Petrifilm SALX System can detect many
35
different serovars of
Salmonella
. One hundred four (104) pure cultures (Table 2 in Appendix) were
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