3M Listeria assays additional AOAC approval
Validations cover food matrices including full fat cottage cheese, chocolate milk, beef hot dogs, deli turkey, and cold smoked salmon, and stainless steel and concrete environmental surfaces.
The firm’s assay to detect Listeria monocytogenes was approved by the AOAC Performance Tested Methods program in September.
The assay, introduced in July 2013, provides results in 24 hours of enrichment – days faster than the standard methods.
OMA and PTM validation
John David, global marketing supervisor for 3M Food Safety, said most regulators require methods that have been collaboratively studied, to demonstrate it can be consistently performed by many labs and compares well to reference methods.
“The AOAC Performance Tested Method Certificate demonstrates the method "works", while the AOAC Official Method of Analysis demonstrates that the method is repeatable in many labs.”
David said the process to achieve the approval involves multiple steps.
“First, an application is sent to AOAC listing at least one matrix to be studied through a written, approved protocol,” he said.
“Then, supplies and inoculated matrices are sent to labs willing and qualified to conduct the comparison of both the reference method and the method under evaluation.
“A minimum of 10 complete data sets are required, so frequently more than 15 labs will be organized at the outset, in case there are issues with samples arriving a wrong temperatures, data lost due to lab errors, etc.
“These studies must be conducted as independent evaluations, so the labs are not paid to participate.”
The final manuscript of the study is submitted for review by an AOAC panel and a positive outcome is the last step to AOAC Official Method of Analysis being granted.
Detection assay process
The 3M Molecular Detection System is based on isothermal DNA amplification and bioluminescence detection technologies.
It provides presumptive positive results and negative after 24 hours of enrichment followed by an assay protocol that is the same for all of their molecular detection assays.
Presumptive positive results are reported in real-time, while negatives are displayed after the 75-minute instrument run is completed.
David said pathogen testing receives a high level of attention and scrutiny.
“Our customers tend to be conservative, requiring collaboratively studied methods, detailed performance data, and even rigorous in-house evaluation to ensure that the method’s performance meets their expectations,” he said.
“For our customers to adopt a new method, the method must not only perform as expected, but also deliver a greater value to the customer by improving their overall pathogen testing program with increased ease-of-use, productivity, and efficiency.
“In the industry, we are seeing an increasing number of food processors and pathogen testing laboratories requiring and implementing molecular detection methods for pathogen testing.
“Molecular methods can offer faster time-to-result and higher sensitivity and specificity, as compared to traditional culture methods or immunoassay-based methods. Looking forward, molecular methods will eventually overtake culture methods to become the new “gold standard.”
3M also has AOAC First Action Official Methods of Analysis status for its Molecular Detection Assay Salmonellaand AOAC PTM and NF Validation by AFNOR Certification for its Molecular Detection Assay Salmonella and E.coli O157 (including H7).
