Pall GeneDisc® method for the detection of Listeria monocytogenes in
food and environmental samples – AOAC 031204
SCOPE
The GeneDisc® Plate method is applicable for detection of Listeria monocytogenes in foods
and environmental samples including meat and meat products.
PRINCIPLES
The Pall GeneDise® technology uses a real-time PCR technique that combines a dedicated
consumable, the GeneDisc® Plate, with a proprietary PCR platform, the Gene Disc® Cycler.
Initially the organisms are allowed to grow in half Fraser broth (HF broth) followed by DNA
extraction using Extraction Pack Food 1 protocol. DNA samples then undergo PCR analysis
for the presence of specific gene unique to L. monocytogenes. All samples identified as
positive using this test must be confirmed at a department approved laboratory using AS
5013.24.1.

Pre-Enrichment
A sample weighing 25 g is diluted in 225 mL HF broth, homogenized by stomaching, and
incubated at 37 ± 1ᵒC for 25 ± 1 hour. Environmental swabs are enriched with 9 mL of
HF broth, homogenized by stomaching or mixed by vortexing and incubated at 37 ± 1ᵒC
for 25 ± 1 hour.

GeneDisc® PCR assay
Bacterial DNA is extracted from the enriched samples using the Extraction Pack Food1
protocol and analysed using GeneDisc® Plate Listeria monocytogenes for detection of
specific gene. DNA extraction and PCR must be performed as per the manufacturer’s
recommended protocols.

Confirmation
Samples that test PCR negative are reported as negative. Confirmation of potential
positive samples must be carried using pre-enrichment medium (HF broth) at the
appropriate stage in AS 5013.24.1 i.e. plating out and identification.
Issue 2016 01 25 | Approved Methods Manual
Export Standards Branch | Exports Division
Department of Agriculture and Water Resources
Page 1 of 2
GeneDisc® PCR Assay for L. monocytogenes - AOAC 031204
CHECKLIST
Enrichment
Is an appropriate initial suspension prepared in
HF broth?
Is enrichment carried out 37 ± 1C for 25 ± 1 h?
Is the correct amount of enrichment broth used
i.e. 225 mL for foods?
Is a positive control culture run with each batch of
samples?
Is the control culture inoculated into the primary
enrichment broth at a level of 10 to 100 cells?
GeneDisc®
Assay
Are the manufacturer’s instructions reproduced
in the laboratory manual and followed without
modification?
Are technicians familiar with and trained in the
operation of the GeneDisc® Technology?
Is the shelf-life of media and kits controlled?
Confirmation
Is Listeria confirmed using AS 5013.24.1 at a
department approved laboratory?
Issue 2016 01 25 | Approved Methods Manual
Export Standards Branch | Exports Division
Department of Agriculture and Water Resources
Page 2 of 2