Chapter III. The BAX® System X5 PCR Assays
BAX® System X5 User Guide
31
Using the Genus
Listeria
Assay
Kit #KIT2024 (D15407193)
1. Enrich Samples
The
AOAC Research Institute
has validated the BAX® System for
detecting Genus Listeria on environmental surfaces (stainless steel,
plastic, ceramic tile, rubber, painted and unpainted wood, drain swabs,
sealed concrete, cast iron, and air filter material) and on foods (dairy,
meat, fish and vegetables).
This test
kit’s performance was reviewed by AOAC Research Institute and was found to
perform to the manufacturer’s specifications.
Sample type
Primary enrichment
Secondary enrichment
BAX® System Listeria media
Environmental
sponges
Sample a 4 x 4 in (10 x 10 cm) environmental area
with a sponge pre-moistened with 10 mL D/E
Neutralizing Broth or equivalent. Homogenize
sponge with 190 mL pre-warmed (36°C) BAX®
System
Listeria
media broth. Incubate at 36°C for
26-30 hours.
None
Environmental
swabs
Sample a 1 x 1 in (2.5 x 2.5 cm) environmental
area with a swab pre-moistened with 300-500 µL
D/E Neutralizing Broth or equivalent. Add the
swab to 10 mL pre-warmed (36°C) BAX® System
Listeria
media broth. Incubate at 36°C for 22-26
hours.
None
Standard media
Environmental
sponges
Sample a 4 x 4 in (10 x 10 cm) environmental
area with a sponge pre-moistened with D/E
Neutralizing Broth. Homogenize sponge with 190
mL pre-warmed (30°C) Demi-Fraser broth or
UVM. Incubate at 30°C for 22-26 hours.
Transfer 100 µL enriched
sample to 9.9 mL pre-warmed
MOPS-BLEB. Incubate at
35°C for 18-24 hours.
Frankfurters
For 25 g -
Homogenize 25 g samples with 225 mL
pre-warmed (30°C) Demi-Fraser broth. Incubate
at 30°C for 22-26 hours.
For 125 g
- Homogenize 125 g samples with
1.125L of UVM media. Incubate at 30°C for 23-26
hours
Transfer 100 µL enriched
sample to 9.9 mL pre-warmed
(35°C) MOPS-BLEB. Incubate
at 35°C for 18-24 hours.
Smoked salmon
Homogenize 25 g samples with 225 mL pre-
warmed (30°C) Demi-Fraser broth. Incubate at
30°C for 22-26 hours.
Transfer 100 µL enriched
sample to 9.9 mL pre-warmed
(35°C) MOPS-BLEB. Incubate
at 35°C for 18-24 hours.
Spinach and
other vegetables
Homogenize 25 g samples with 225 mL pre-
warmed (30°C) Demi-Fraser broth. Incubate at
30°C for 22-26 hours.
Homogenize 25 g samples with 225 mL of pre-
warmed (30
o
C) BLEB and incubate for 4 hours at
30
o
C. After 4 hours add selective agents
acriflavin, nalidixic acid, and cycloheximide and
incubate for an additional 18-22 hours.
Transfer 100 µL enriched
sample to 9.9 mL pre-warmed
(35°C) MOPS-BLEB. Incubate
at 35°C for 18-24 hours.
