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Independent Study for the Detectx Combined Assay for the Detection of Aspergillus, Salmonella, and STEC (stx1 and/or
Benjamin A Katchman1, Michael Tomchaney1, Dawn Bueschel1
1PathogenDx Inc., Tucson, AZ 85719, USA.
Background:
The PathogenDx family of assays uses microarray technology to simultaneously detect the presence of bacterial and fungal pathogens in food products, environmental surfaces, and cannabis products.
Objective:
The Detectx Combined assay was validated for the detection of Aspergillus, (Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, and Aspergillus terreus), Salmonella, and a broad range of STEC (stx1 and/or 2) species. The validation consisted of two matrix studies in dried hemp flower and dried cannabis flower (>0.3% delta-9 tetrahydrocannabinol) flower, product consistency, stability, robustness, and inclusivity and exclusivity for two targets: Aspergillus and STEC.
Method:
The PathogenDx Detectx Combined assay was evaluated with 30 replicates in each matrix and confirmed according to the instructions outlined in this study.
Results:
Results of the validation study met the requirements of AOAC Standard Method Performance Requirement (SMPR®) 2020.002 and 2020.012. In the inclusivity and exclusivity study, all target isolates (Aspergillus and STEC) were correctly detected. For the exclusivity study, 26 out of 30 Aspergillus and 30 out of 30 STEC non-target strains were correctly excluded. In the matrix study, the PathogenDx Detectx Combined assay showed no significant statistical differences between confirmed results for dried hemp and cannabis flower. Robustness testing indicated that small changes to the method parameters did not impact the performance of the assay. Stability and consistency studies verified that the assay's shelf-life claims were appropriate, and manufacturing of the assay was consistent.
Conclusions:
The validation study indicated that the PathogenDx DetectX Combined assay was successful in detection of the new target analytes (Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, and Aspergillus terreus and STEC containing stx1 and/or 2) and could successfully recover these organisms and Salmonella from dried hemp flower and dried cannabis flower (>0.3% delta-9 tetrahydrocannabinol).
Highlights:
The PathogenDx DetectX Combined Assay will be the first PTM approved multiplex assay for Aspergillus, E. coli and Salmonella that does not require an enrichment step.
