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VIDAS LMX & LPT Collaborative Study
April 19, 2013
OMA-2013-Apr-XXX
will also be included in the shipment to document the temperature of the sample upon receipt.
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Record all results on the data sheet provided.
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NOTE
– use stomacher bag with filter for all VIDAS test portions. Instructions are provided for
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both Heat and Go and boiling. Please follow the boiling instructions of you do not have a Heat
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and Go instrument.
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1.0
VIDAS LMX
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1.1
25g:
Pre-warm the LMX broth at 18-25°C. Add 225 mL supplemented LMX
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(500µL supplement/225mL LMX broth) to each 25g test portion. Stomach each
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sample for approximately two minutes and incubate 26-30 h at
37 ± 1°C
.
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1.1.1
Heat and Go: Transfer 0.25 mL to VIDAS LMX strip and heat on the Heat
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and Go for 5±1 min. Cool 10 min then perform VIDAS assay.
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1.1.2
Boiling: Transfer 1-2 mL of enrichment broth into a tube. Seal tube and
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heat for 5±1 min at 95-100°C. Cool, mix and transfer 0.25 mL into the
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VIDAS LMX strip then run the VIDAS assay.
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1.2
125g:
Add 375 mL LPT broth (prewarmed at 18-25°C) to each 125g test portion.
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Stomach each sample for approximately two minutes and incubate 24-30 h at 30 ±
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1°C. Transfer 1 mL primary enrichment into 10 mL LPT broth. Incubate 22-26
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hr at 30 ± 1°C.
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1.2.1
Transfer 0.25 mL to VIDAS LMX strip and perform VIDAS assay. NO
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HEATING.
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1.3
Confirmation
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1.3.1
Confirm each test portion, regardless of presumptive result.
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1.3.2
Streak each enriched test portion to OX and ALOA following incubation
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instructions.
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1.3.3
Choose 5 typical or suspect colonies, or if there are <5 such colonies,
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choose all to confirm
Listeria
. Streak chosen colonies individually onto
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surfaces of separate tryptic soy agar with yeast extract agar plates.
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Incubate 24 hr at 37
°
C.
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1.3.3.1 Only one colony needs to confirm positive to call the test portion
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positive for
Listeria.
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1.3.4
Biochemical tests will be performed using the VITEK2 GP or API
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Listeria. Follow instructions described in AOAC 993.12 (Appendix 9.7)
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for additional tests.
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1.3.4.1 VITEK2 GP: perfom Gram stain (Gram +) followed by VITEK2
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GP card.
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1.3.4.2 API Listeria: perform Gram stain (Gram +), catalase (+), oxidase (-
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), hemolysis and motility (motile at 25
°
C) tests followed by the
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API Listeria strip.
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2.0
VIDAS LPT
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DRAFT DOCUMENT
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