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What's new with the PathoSEEK® Total Aerobic Bacteria Count Assay User Guide Version 2?

On November 16, 2022 MGC launched a new version of the Total Aerobic Bacteria Count (TAC) Assay User Guide which replaces the version 1 released in September of 2021.

We are excited to announce the new PathoSEEK® Total Aerobic Bacteria Count(TAC) Assay with SenSATIVAx® Purification User Guide Version 2. In summary, this new protocol: 

  • Affects both flower samples and marijuana infused products (MIPs) 
    • Note: There will no longer be a Cq to CFU conversion for MIP samples provided by MGC. We recommend enriching non-flower samples in TSB and processing as pass/fail.  This process, which is described in the updated TAC user guide, will ensure viable aerobic bacteria is detected if present. If aerobic bacteria is detected post enrichment, labs should perform plating to achieve a total viable count for reporting of CFUs. If aerobic bacteria is not detected in a MIP sample post  enrichment, then the sample can be reported as not detected.
  • Requires PathoSEEK Master Kit v3 (SKU 420201) for both flower samples and marijuana infused products (MIPs). There is no change to the SKUs required from TAC User Guide Version 1.
  • Changes the initial, upfront dilution to 19mL of Tryptic Soy Broth per 1g of sample for flower samples
  • Adds a centrifugation step to pellet cells prior to lysis (flower only)
  • Adds a back calculation to the recommended Cq to CFU/g conversion equation to account for the revised upfront dilution (only applies to flower matrix)

This update is a result of months of testing our TAC assay process, during which we: 

  • Increased assay sensitivity by adding a spin step in the flower extraction process pre-lysis
  • Created updated Cq to CFU conversion curves for flower samples based direct comparison results to multiple aerobic bacteria organisms 
  • Confirmed enumeration against commercially-available certified reference material

PT/CRM Recommendation

If  your lab is required to validate a new assay with a certified reference material or proficiency test, we recommend the following standard from NSI: 

  • Quantitative APC in HEMP CRM, Catalog Number FM-726


What if I don’t want to switch? 

We understand there may be reasons why your lab would like to continue using the current Total Aerobic Bacteria Count protocol (User Guide Version 1), such as potential need for revalidation. However, we encourage labs to use the new protocol (User Guide Version 2) to ensure optimal assay performance and consistency with all sites using our kits. Going forward, we will train all new customers on the User Guide v2.


Looking ahead

We are looking forward to achieving AOAC certification on all MGC products for which there is a published SMPR. We have already received AOAC certification for the PathoSEEK® Salmonella & STEC E. coli Multiplex Detection Assay and the PathoSEEK® 5-Color Aspergillus Multiplex assays. We have begun the process of earning AOAC certification for the PathoSEEK® Total Yeast & Mold Detection Assay with SenSATIVAx® Extraction, and we will share updates as they become available. 

PathoSEEK® Total Aerobic Count Detection Assay Validation Data