3M Listeria MDAL96 Manual Del Usuario página 5

INSTRUCTIONS FOR USE
Follow all instructions carefully. Failure to do so may lead to inaccurate results.
Periodically decontaminate laboratory benches and equipment (pipettes, cap/decap tools, etc...) with a 1- 5% (v:v in water) household bleach
solution or DNA removal solution.
SAMPLE ENRICHMENT
3M recommends the use of either 3M Modified Listeria Recovery Broth (Table 2), or Demi-Fraser Broth Base and Fraser Broth Base (Table 3) for the
enrichment of food and environmental samples.
WARNING: Do not use Demi-Fraser Broth Base or Fraser Broth Base containing ferric ammonium citrate (FAC), either already in the broth base or as
an added supplement, when using the 3M Molecular Detection Assay Listeria.
Foods
Table 2 and 3 presents guidance for the enrichment of food samples of 25 g at a 1:10 dilution. It is the user's responsibility to validate alternate
sampling protocols or dilution ratios to ensure this test method meets the user's criteria.
• Pre-warm the enrichment medium to 37 ±1°C.
• Aseptically combine the enrichment medium and sample. For all meat and highly particulate samples, the use of filter bags is recommended.
Homogenize thoroughly for 2 minutes, using a stomacher, blender or by hand massage. Incubate at 37 ±1°C (see Tables 2 and 3).
• For Demi-Fraser Broth Base protocols only: If required, transfer 0.1 mL of the primary enrichment into 10.0 mL Fraser Broth Base (see Table 3).
Incubate at 37 ±1°C for 24-26 hours.
Environmental Samples
Sample collection devices can be a sponge hydrated with a neutralizing solution to inactivate the effects of the sanitizers. 3M recommends the use
of a biocide-free cellulose sponge. Neutralizing solution can be Dey-Engley (D/E) Neutralizing Broth. It is recommended to sanitize the area after
sampling.
WARNING: Should you select to use Neutralizing Buffer (NB) that contains aryl sulfonate complex as the hydrating solution for the sponge, it is
required to perform a 1:2 dilution (1 part sample into 1 part sterile enrichment broth) of the enriched environmental sample before testing in order
to reduce the risks associated with a false-negative result leading to the release of contaminated product.
The recommended size of the sampling area to verify the presence or absence of the pathogen on the surface is at least 100 cm
4"x4"). When sampling with a sponge, cover the entire area going in two directions (left to right then up and down) or collect environmental samples
following your current sampling protocol or according to the FDA BAM
1. Pre-warm the enrichment medium to 37 ±1°C.
2. Aseptically combine the enrichment medium and sample. Homogenize thoroughly using a stomacher, blender or by hand massage. For the 3M
Modified Listeria Recovery Broth protocol, homogenize for 2 ±0.2 minutes. For the Demi-Fraser Broth Base protocol, homogenize for 30 seconds.
Incubate at 37 ±1°C (see Tables 2 and 3).
, USDA FSIS MLG or ISO 18593
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(10 cm x 10 cm or
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guidelines.
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