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3M Petrifilm SALX Collaborative Study
July 2013
OMA-2013-July-XXX
DRAFT DOCUMENT
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5.10
Interpretation
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5.10.1
Remove the 3M Petrifilm SALX Plates from the incubator and visually examine
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the isolated colonies. See Table 2. Do not count artifact bubbles that may be
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present.
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5.10.2
Note: Using indirect back lighting may enhance reading of colony color, discrete
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yellow zones, and gas bubbles associated with a colony.
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5.10.3
Presumptive positive
Salmonella
species are red to brown colonies with a yellow
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zone or associated gas bubble, or both (figure G). An associated gas bubble is
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defined as being located within one colony diameter distance from the colony
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(see Table 2 below).
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Table 2:
Interpretation for Presumptive Positive
Salmonella
species
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Colony Color
Colony Metabolism
Result
Red
Dark
Red
Brown
Yellow
zone
Gas bubble
Presumptive +
Presumptive +
Presumptive +
Presumptive +
Presumptive +
Presumptive +
Presumptive +
Presumptive +
Presumptive +
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Non-
Salmonella
species (figure H):
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•
Blue colonies, green colonies, blue to green colonies, and/or black colonies with or without a
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yellow zone and/or associated gas bubble are non-
Salmonella
organisms.
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•
Red, dark red, and brown colonies with no yellow zone and no associated gas are non-
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Salmonella
organisms.
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•
Red, dark red, and brown colonies with a magenta zone are non-
Salmonella
organisms.
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If presumptive positive
Salmonella
colonies are not present, then
report the results as
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Salmonella
not detected in the matrix.
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If presumptive positive
Salmonella
colonies are present, then continue with the following
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Biochemical Confirmation steps:
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OMAMAN-08/Collaborative Study Protocol
March 2014
Expert Review Panel Use Only
AOAC Research Institute
Expert Review Panel Use Only