The modular multiplex RT-PCR method simultaneously detects Shiga Toxin E. coli (STEC), Salmonella spp. and Listeria monocytogenes using a single, overnight enrichment (24 hours).
Ready-to-use PCR reagents contain oligonucleotides (primers and probes) targeted to specific pathogen-related genes in these bacteria.
AOAC and launch platform
Application for AOAC status covers five matrices - environmental swabs, RTE meat, ground beef, RTE vegetables and cheeses.
The firm said it will be adding matrices and pathogens in the future but has tested spices, fresh cheese, ready-to-eat deli meat, smoked salmon and peanut butter.
PolySkope 1.0 is a screening system to target the widest possible range and not a confirmation tool so can target Shiga-toxin virulence factors and is not strain specific.
The firm recommends confirmation with an immunoassay, lateral flow or something different than PCR.
PolySkope has selected the ThermoFisher/ABI QuantStudio5 instrument as the launch platform.
Up to 94 reactions with five pathogenic targets each can be run on the Quantstudio 5 96-well instrument.
The instrument is optimized for multiplexes and has secure local and remote (cloud) data storage. It also allows remote run and analysis for use in satellite labs.
Cyrus Zegrati, co-founder and CEO of PolySkope, said it had a round of funding in 2013 and last year signed the instrument agreement with Thermo Fisher Scientific.
“At the time of the funding we opened an ISO 17025 accredited lab. We saw a lot of development work in a research setting with no direct experience of what works and does not,” he told FoodQualityNews.
“With the vast majority of testing the retailers and end-users want AOAC, so it is the de-facto approval, it is not regulation but it is the de-facto regulation.”
When asked why multiplex assays had not become widely-used already, Zegrati said many didn’t believe it would happen and acted as if it was impossible, so did not try.
“The PCR assay was developed first, it took longer to develop the media, lysis buffer and the procedure to work in foods,” he said.
“[Enrichment and background flora] was a huge challenge. I can’t give too much away as it is proprietary but it took a lot of development work to make sure it was not an issue, it was about one year’s worth of work on that.
“Initially, we were not doing the best job of explaining it can detect all three pathogens at once, RTE manufacturers loved it but it seemed to scare others. We had to rebrand our message to say it doesn’t have to do it all.
“A contract lab might have a request for a STEC test and 24 hours later the client might decide they want to do the Salmonella and Listeria tests after all and you don’t have to start over.”
Zegrati added the next goal was to reduce the enrichment time.
PolySkope's Multiplex Enrichment Media (PMEM) allows simultaneous enrichment of all organisms in the same bag.
End users can detect one, two or three pathogens by selection on the instrument; the protocol and sample preparation are identical.
The firm said this provides savings for end-users by reducing up to 3-fold the media, reagents, equipment, technician labour, protocol complexity and regulatory burden for pathogen testing.
Dr Michael Centola, co-founder and CSO, said it is translating the expertise of its team in multiplex diagnostic assay development from the clinical space into food safety applications.
“The complexity in the context of what is known is low. When you work in molecular diagnostics there is more stringency. In molecular diagnostics you work with blood out of a clinic or hospital, there is no time to treat it so there is variability,” he told us.
“The platform can be expanded as pathogens become more relevant as it is straightforward to add others. The potential is there as commercial and regulations increase to increase the multiplicity.”
Dr Centola said simplicity and speed is of the upmost for food safety testing labs.
“We are hearing from the groups beta-testing our products that they are the simplest PCR test on the market in terms of how it gets run,” he said.
“We are excited about the flexibility; you have one protocol with one media which takes the complexity out of it for labs. They have the instrument cost which is not inconsiderable, but salaries are the largest part of the budget.”
PolySkope was founded in 2011 by scientists with a record of developing multiplex diagnostic assays in the clinical space (Crescendo, Intergenetics).
The firm has one lab at University Research Park at the University of Oklahoma and employs more than 10 people.
It anticipates launch of PolySkope 1.0 and AOAC PTM status in Q3 2017 with availability in Europe and Asia by Q2 2018.