Cannabis microbial testing is performed to protect the consumer. Some medical marijuana patients are immunocompromised from chemotherapy and have an inherently higher risk of pathogenic microorganisms. Fatal and potentially fatal cases of smoking contaminated cannabis from immunocompromised individuals have been reported in scientific literature.There have even been reports of various outbreaks on reasonably healthy people that were not as fatal . Most microbes do not present a danger a low levels. There is bacteria all around us and most of it is not pathogenic. It is impossible to avoid bacteria on cannabis unless it is grown in clean room with HEPA filtration and you were somehow able to obtain sterile soil. It is important to be able to identify the specific microbes on cannabis samples so that an accurate determination can be made regarding its safety.
Cannabis microbial testing is generally done via either a culture based plating technique or a molecular based approach using qPCR (quantitative Polymerase Chain Reaction). Culture based techniques involve plating on a Petri dish using sterile techniques, growing, and examining with microscopy. This procedure is relatively cheap, however, it is time consuming and has other pitfalls.
Quantitative PCR (qPRC) has many advantages over culture based techniques. It detects for specific DNA sequences shared by family of microbes so that more accurate results are obtained. False negatives and false positives can potentially be observed with culture based techniques. qPCR overcomes this limitation due to its higher specificity that comes with detecting targeted DNA sequences. The main drawback to qPCR is cost. qPCR costs significantly more to perform than generic culture based plating techniques. This high cost to of entry and higher cost per sample is most likely the reason of why it hasn’t been adopted widely by cannabis testing labs. Oklahoma has no cannabis testing labs currently utilizing qPCR to my knowledge, although I hope to see it as the testing marketplace becomes more competitive.