The Minnesota Office of Cannabis Management (OCM) is providing clarification to testing facilities regarding confirmatory testing performed after detection of a pathogen during microbial screening.   

This guidance serves as an amendment to previous verbal OCM guidance. OCM had previously stated that the confirmatory test for a molecular method would need to be plating to demonstrate viability of the microbe. This guidance clarifies:  

1. If the initial analysis was done using molecular testing, the confirmatory test may be either molecular testing or plating. 
2. If the initial analysis was done using plating, the confirmatory test must be done using molecular testing. 

The /ocm/assets/OCM_Cannabis_Technical_Authority_v2.0_tcm1202-678506.pdfCannabis Technical Authority (CTA) indicates that “If a pathogen is detected during a screening method, a confirmatory test is required to verify the pathogen.” The goal of confirmatory testing is to ensure that a pathogen detection result from the lab was not a false positive and to ensure that a detected microbe is the species of concern. Confirmatory testing may be done by the initial lab that detected a pathogen in a screening method or may be outsourced to another lab through subcontracting. 

Given that molecular detection of pathogens confirms both the presence and identification of the pathogen, if a pathogen was detected after sample enrichment, it can be confirmed by a second molecular analysis of that enriched or extracted sample. The second molecular analysis may be done by the testing facility using the same molecular technique as the original screening analysis or may utilize a second molecular technique. 

If a testing facility that uses a molecular method for pathogen screening has already verified and utilizes plating for the confirmatory method, the testing facility may continue with that plan. Alternatively, plating may be used as a tool for communication with clients to validate the viable risk of the pathogen detected in a product and the lab may switch to use molecular testing for confirmatory testing.   

Due to the real risk of misidentification of pathogens detected by screening methods that rely on plating, if plating is used for the initial pathogen screening, OCM requires that testing facilities use a molecular detection method to confirm the specified pathogenic species was present.