There is no need for confusion about what method to use for Listeria food and environmental testing. The answer is here:
RAPID'L.mono and a Chromogenic Media
While current classical methods for Listeria detection are laborious and time-consuming, the Bio-Rad RAPID'L.mono and AL methods allow the direct detection and enumeration of Listeria monocytogenes and Listeria spp. in food products for human consumption and environmental samples with a fast, simple, and cost-effective protocol. AL media formulated according to Ottaviani and Agosti has the specificity to provide detection of Listeria monocytogenes and Listeria sp. in 40hr with a convenient protocol. Detection is performed after a single enrichment step in Half Fraser broth for 18-28hr followed by detection on one AL plate in 24 hr. RAPID’L.mono is a unique, highly selective chromogenic medium where the typical colonies appear blue on a red agar, allowing for easy reading. Detection is performed after a single enrichment in Half Fraser broth for 24 hour followed by detection on one RAPID'L.mono plate in 24hr. The enumeration protocol is performed after a dilution of the sample in BPW and direct spreading onto the RAPID'L.mono plate. After a 24 hour incubation, colonies can be enumerated. With extensive validation and inclusion as a second medium in many reference methods, RAPID’L.mono and AL are internationally recognized and can be used for both mandatory and internal QC (auto control) testing.

iQ-Check Listeria spp. and iQ-Check Listeria monocytogenes 
The iQ-Check Listeria monocytogenes II and the iQ-Check Listeria spp. PCR Detection Kits are tests based on gene amplification and detection by real-time PCR after food and environmental samples are enriched in Listeria Special Broth (LSB). 

Ready-to-use PCR reagents contain oligonucleotides (primers and probes) highly specific for L. monocytogenes and all Listeria spp.  A synthetic DNA internal control is included in the reaction mix. An internal control is critical in any reaction to monitor for inhibitors and allows for the validation of any negative result. The iQ-Check L. monocytogenes II and iQ-Check Listeria spp. methods have been rigorously tested and validated by internationally recognized validation agencies. 

Download our performance summaries for the iQ-Check Listeria monocytogenes II and the iQ-Check Listeria spp. methods.

Recently, NF validation for both methods was renewed and/or extended to:

• Shorten the enrichment time for environmental samples to 18hr and reduce PCR run time by 34%, decreasing time to results and providing increased user flexibility
• Include the use of the iQ-Check Free DNA Removal Solution for removal of signal from free DNA or dead cells.

Bio‑Rad offers a complete solution that simplifies your Listeria testing options for faster, more comprehensive results.

• Watch our customer testimonial video on the South Africa Listeria Outbreak:

To learn more about our food safety products visit our website: bio-rad.com/foodscience