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Vanilla ice cream
Independent study
L.monocytogenes
Serotype 1
ATCC 19111
AOAC 993.12
Cooked shrimp
Independent study
L.monocytogenes
Serotype 3b
SLCC 2540
FDA-BAM
Processed cheese
L.monocytogenes
Serotype 1
SM AQ2632
Gorgonzola
AOAC 993.12
Vanilla ice cream
L.monocytogenes
Serotype 1
SM 20V ex beef
AOAC 993.12
Frozen spinach
L.monocytogenes
Serotype 4
SM ScottA
FDA-BAM
SLCC=Silliker Laboratories Culture Collection
1
SM=Silliker Microtech
2
IMVS=Institute of Medical and Veterinary Science
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4
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FDA BAM reference method
(spinach, shrimp, smoked fish, peanut butter)
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7
Twenty 25g inoculated samples and five 25g uninoculated samples were added to 225 ml of Buffered Listeria Enrichment broth base
8
(BLEB). These were stomached for 2 minutes then incubated at 30±1°C. After 4 h incubation the selective agents were added and
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incubation was continued for another 44h at 30±1°C. At 24 and 48h selective enrichment broths were streaked to Oxford agar plates,
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which were incubated for 24-48h at 35±1°C. Typical colonies were confirmed (minimum1/sample).
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12
USDA/FSIS Reference Method
(deli ham)
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Twenty 25 gram portions of the deli ham were enriched with 225 ml of Modified University of Vermont Broth (UVM), stomached at
15
high speed for 2 minutes and incubated at 30 ± 1°C for 22 hours. After incubation, a 0.1 ml aliquot of the UVM enrichment was
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transferred to 10 ml of Fraser broth (FB) with Ferric Ammonium Citrate and incubated at 35 ± 1°C for 26 hours. The UVM was
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streaked to a Modified Oxford (MOX) agar plate and incubated at 35 ± 1°C for 26 hours. The UVM-streaked MOX plates were
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examined after 26 hours for morphologies typical of
Listeria
spp. Presumptive colonies were transferred to horse blood overlay (HL)
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agar and incubated at 35 ± 1°C for 22 hours. FB tubes were examined for typical darkening reaction. Tubes exhibiting a typical
20
reaction were streaked to MOX and incubated 35 ± 1°C for 26 hours. Non-typical tubes were re-incubated an additional 24 hours and
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PTM Certification Report