We’ve put together our most frequently asked questions regarding the ANSR® Listeria Right Now™ system to help you get the answers you’re looking for. If you don’t see the answer you’re looking for, ask us.
How should I use ANSR Listeria Right Now?
The Listeria Right Now assay adds value anywhere a faster response is beneficial. Here are some of the innovative ways our customers tell us they use it:
- To perform corrective actions much more quickly to prevent an issue from becoming a serious problem.
- To perform investigations following a positive test result.
- To commission and implement new equipment more quickly. This process can take days with traditional Listeria testing, but can be done with Listeria Right Now in less than one shift.
- As a process control.
- To enhance their vectoring process, including testing transitory items such as containers, pallets and shoes.
- To test tools and other maintenance items to minimize cross-contamination.
- To inspect and validate areas following construction events.
- To bring Listeria testing into their facility without the concern of growing pathogens.
What is the sensitivity of ANSR Listeria Right Now?
The Listeria Right Now assay has a theoretical level of detection of 2 CFU per swab and a 95% confidence level of 4 CFU per swab.
How well does ANSR Listeria Right Now work with sanitizers and cleaners?
We’ve tested the ANSR Listeria Right Now system with all of the popular sanitizers and cleaners and found no degradation of performance in the presence of residual sanitizers and cleaners.
What are most common reasons for getting invalid results?
- Inadequate time in the 80°C heat block.
- The presence of particulate matter in the reaction tubes.
- Sampling heavily soiled areas.
Does ANSR Listeria Right Now detect dead cells?
Yes, the ANSR Listeria Right Now system does not discriminate between live and dead cells. However, since the target for the Listeria Right Now assay is ribosomal RNA, which degrades faster than DNA after cell death, there is less of a probability of replicating ribosomal RNA (rRNA) from dead cells than with traditional PCR assays.
Can I use ANSR Listeria Right Now to replace my current testing program for Listeria?
Neogen recommends that the ANSR Listeria Right Now system be seen as a complement to your existing Listeria testing program, not as a replacement. See the responses from question one above for its optimal uses.
How do we confirm results?
The ANSR Listeria Right Now system does not include a confirmation protocol. Since all Listeria cells are destroyed once the swab is inserted into the lysis buffer solution, confirmation cannot be performed using a common extraction solution.
Is ANSR Listeria Right Now validated using environmental sponges?
The ANSR Listeria Right Now system is only validated using the included sampling swabs. The use of sponges is under review, but has not been validated yet. If a sponge protocol is established, there will likely be changes to the current test procedure.
Can I use ANSR Listeria Right Now to test food products?
No, the Listeria Right Now assay has not been validated with any food product matrices; however, the ANSR system provides conventional pathogen assays for testing food and environmental samples. These assays include Campylobacter, E. coli O157:H7, Listeria, L. mono, and Salmonella.
Do you have AOAC approval?
Yes, AOAC approval was awarded in August of 2018 for stainless steel, sealed concrete, plastic, ceramic tile and rubber surfaces.
Can I use this on Zone 1 product surfaces during operational runs for USDA-regulated products?
The Listeria Right Now assay is designed for post-cleaning, pre-production environmental use. This includes all zones. It has not been validated against product matrices at this time, though we are working on a few currently.
How exactly are you able to detect 4 CFU per swab without enrichment?
The Listeria Right Now assay targets ribosomal RNA (rRNA). This is a significant advantage because there are typically 1,000 to 10,000 copies of rRNA compared to only one copy of DNA, which traditional PCR targets. Hence, there can be a 1,000- to 10,000-fold increase in target analyte concentration. In addition, the reaction within the reagent tubes is isothermal, meaning the molecular replication is constant compared to thermal cycling replication that occurs within PCR systems. In summary, when you start with a greater number of targets and faster replication, you get a faster result.
You mentioned that the ANSR Listeria Right Now system targets rRNA, but the replication occurs on DNA strands. How does this happen?
The reaction includes a reverse-transcription step that converts rRNA to DNA prior to replication.
How does the ANSR system read the reaction occurring in the reader?
The ANSR reader measures fluorescent light using optics. As the isothermal reaction occurs, a fluorescent beacon is released (unquenched) when it binds to the target analyte’s DNA strand. As more target DNA replicates are produced, more beacons are released resulting in more fluorescence. The ANSR instrument tracks the light output from the sample and compares it to the output from the positive control to determine the positive or negative status of the sample.
What specifically is occurring to the sample at each of the 37, 80, and 56-degree incubations?
- The sample undergoes lysis during the 37°C incubation.
- The lysis enzymes are deactivated through denaturation during the 80°C incubation.
- The replication reaction occurs in the reader at 56°C.
How can I look at result trends over time?
The ANSR system software can be exported to an Excel spreadsheet for review.
How long is the ANSR system under warranty?
The system is sold and supported with a 1-year warranty with the exception of abuse or breakage. Preventive maintenance should follow the protocols established by your organization.
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