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SUBMITTED 050113, REVISED 102513
random number sequence 1-150 was generated using an on-line program [7] and these numbers laid
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beside the individual entries in the strain list. The list was then sorted in numerical order 1-150. This
2
resulted in a randomized list of strains with inclusive and exclusive organisms intermixed. The list was
3
then divided into blocks of 15 strains for processing in a sequence of 10 experiments. One additional
4
inclusivity strain was obtained later and was added to one of the last testing blocks. One intended
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exclusivity strain was found to be non-viable and was not used.
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Test strains were taken from frozen storage, streaked to tryptic soy agar (TSA) to obtain isolated
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colonies, and incubated at 36 ± 1
o
C for 16-24 h. Isolated colonies were picked and streaked again to TSA
9
and also to 6
Salmonella
selective differential agar media: Hektoen enteric agar (HE), xylose lysine
10
deoxycholate agar (XLD), and bismuth sulfite agar (BS) as described in the FDA/BAM method [3]; and
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brilliant green sulfa agar (BGS), xylose lysine tergitol agar (XLT-4), and double-modified lysine iron agar
12
(DMLIA) as described in the USDA/MLG method [4]. All plates were incubated at 35 ± 1
o
C for 22-24 h,
13
consistent with instructions in the FDA/BAM and USDA/MLG reference culture procedures.
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Preparation of Test Samples
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A representative colony from each of the seven different plates was picked with an inoculating loop and
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resuspended individually in 0.5 mL aliquots of PBS. ANSR assays were performed by a second technician
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without knowledge of the randomization and sample coding process.
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ANSR Testing
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ANSR assays were conducted in accordance with the test kit instructions, using 50 µL of the colony
23
resuspension as sample.
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Data Analysis
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For both the inclusivity and exclusivity panels, the percent correct results was calculated based on
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results scored as positive or negative, corresponding to identification of colonies as “
Salmonella
spp
.
” or
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“not
Salmonella
spp
.
”
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Results and Discussion
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