Marijuana inspection: microbial pathogens and total yeast and mold

Concerning the testing of cannabis product for microbiological contaminants, there is a large pool of standard methods on which to draw. All microbiological methods employed must include applicable controls. Qualitative pathogen methods must confirm presumptive results as either positive or negative by the inclusion of a confirmation step. Confirmation of pathogens should not be addressed by simply re-running positive sample enrichments or retesting remaining sample.


Methods applicable to total aerobic microbial counts:


Methods applicable to bile tolerant gram negative bacteria:

Note: there are many applicable methods not listed in this section due to the fact that these methods are labeled as “total Enterobacteriacea” which, if modified appropriately, might be applicable for use analyzing total gram negatives, but any method that specifically counts only members of Enterobacteriacea is not applicable.



Methods applicable to Candida albicans testing:
  • Baird, Rosamund M., Corry, Janet E. L., Curtis, Gordon D. W.  2012. Handbook of Culture Media for Food and Water Microbiology 3rd Edition. The Royal Society of Chemistry.

  • Odds, Frank C. and Bernaerts Ria.. 1996. CHROMagar Candida, a New Differential Isolation Medium for Presumptive Identification of Clinically Important Candida Species. Journal of Clinical Microbiology, 32(8) 1923-1929

  • International Standards Organization (ISO), 2015. “Cosmetics -- Microbiology -- Detection of Candida albicans ISO/TS 18416:2015.” https://www.iso.org/standard/25571.html

  • Leber, Amy L. 2016. Clinical Microbiology Procedures Handbook, 4th Edition. American Society for Microbiology.

  • Pfaller M. A., Houston, A., Coffmann. 1996. Application of CHROMagar Candida for Rapid Screening of Clinical Specimens for Candida albicans, Candida tropicalis, Candida krusei, and candida (Torulopsis) glabrata. Journal of Clinical Microbiology, 34(1) 58-61

  • United States Pharmacopeia (USP), 2009. “<61>  Microbiological Examination of nonsterile products: microbial enumeration tests.” https://www.uspnf.com/official-text/accelerated-revision-process/accelerated-revision-history/harmonized-microbiology-general-chapters

  • United States Pharmacopeia (USP), 2010. “<610> “Alternative Microbiological Sampling Methods for Nonsterile Inhaled and Nasal Products.”

  • United States Pharmacopeia (USP), 2009. “<62>  Microbiological examination of nonsterile products: tests for specified microorganisms.” https://www.uspnf.com/official-text/accelerated-revision-process/accelerated-revision-history/harmonized-microbiology-general-chapters
Methods applicable to the quantitation of total coliform bacteria:
  • Baird, Rosamund M., Corry, Janet E. L., Curtis, Gordon D. W.  2012. Handbook of Culture Media for Food and Water Microbiology 3rd Edition. The Royal Society of Chemistry.

  • Food and Drug Administration (FDA), 2023. "Chapter 4, Enumeration of Escherichia coli and the Coliform Bacteria." Bacteriological Analytical Manual (BAM). https://www.fda.gov/Food/FoodScienceResearch/LaboratoryMethods/ucm2006949.htm

  • International Standards Organization (ISO), 2021. “ISO/TS 4832:2006 Microbiology of food and animal feeding stuffs -- Horizontal method for the enumeration of coliforms -- County-count technique.” https://www.iso.org/standard/38282.html


Methods applicable to Pseudomonas aeruginosa testing:


Methods applicable to Salmonella spp. and Shiga toxin-producing Escherichia coli testing:
Methods applicable to Staphylococcus aureus testing:


Methods applicable to total yeast and mold testing: