Tag Archives: qPCR

A Research Study on the Antimicrobial Properties of Cannabis

By Cindy Orser, PhD
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Inexpensive in vitro Methods to Evaluate the Impact of Cannabinoid-containing Products on Sentinel Lactobacillus spp. 

S. Lewin 1, A. Hilyard2, H. Piscatelli1, A. Hangman1, D. Petrik1, P. Miles2, and C. Orser2

1MatMaCorp Inc, Lincoln NE; 2Apothercare LLC, Boston MA 

Abstract

The public has readily embraced cannabidiol (CBD) in countless unregulated products that benefit from commercial promotion without FDA oversight, who recently concluded: “that a new regulatory pathway for CBD is needed that balances individuals’ desire for access to CBD products w/ the regulatory oversight is needed to manage risks.”1 The reported antimicrobial properties of CBD combined with the recent proliferation of cannabinoid-containing products marketed to women for intimate care led us to explore the impact on the sentinel lactobacilli species associated with a healthy reproductive tract. Except for lubricants and tampons, the FDA regulates intimate care products as cosmetics. Even non-cannabis serums, washes, and suppositories are not required to be tested for their effect on the reproductive microbiota. We aimed to investigate the utility of easy-to-use, inexpensive in vitro assays for testing exogenous cannabis products on reproductive microbiota. In vitro assays can provide important evidence-based data to inform both manufacturers choosing both an active cannabinoid ingredient source as well as excipient chemicals and consumers in the absence of safety or quality data. In simple, straightforward exposure studies, we examined the antimicrobial activity of CBD and cannabigerol (CBG) on the most dominant vaginal lactobacilli species, L. crispatus, associated with good health.

Introduction

The testing of readily available products containing cannabinoids, predominately CBD following the widespread legalization of hemp by the 2018 US Farm Bill, is not required beyond ensuring THC content is below 0.3%. Therefore, basic information on safety, quality, antimicrobial activity, bioavailability, and dosing is unavailable and undocumented. The situation is further complicated by the complex chemoprofiles of cannabis extracts based on the cultivar, the extraction methods and subsequent cleanup, and other chemical excipients in the formulation. The FDA has finalized guidance on quality considerations for clinical research for the development of cannabis and cannabis-containing drugs intended for human use.

One approach to backfilling non-existent safety and quality data for cannabinoid active ingredients and those products made from them is to apply or devise assays that can provide relevant toxicity data in an in vitrosystem. Farha et al. (2020) reported that seven cannabinoids are potent antibiotics, including CBD and synthetic CBG. CBG inhibited the growth of gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), but not gram-negative bacteria unless their outer membrane was permeabilized (Farha et al. 2020). In addition, several volatile terpenes, the main constituents of essential oils extracted from Cannabis sativa L., also have potent antibiotic activity against gram-positive bacteria (Iseppi et al. 2019). We have previously written about the risks associated with disrupting the healthy microbiome of gram-positive vaginal bacterial species leading to dysbiosis (Orser 2022) and its further health complications.

Several successful approaches to assessing the toxicity of CBD have already been reported including human cell culture work by Torres et al. (2022) who showed that pure CBD has a repeatable impact on cell viability, but that hemp-derived finished CBD products had variable impact. Cultured human cell viability experiments demonstrated similar potencies across three different hemp-derived CBD products in the microgram per milliliter [mg/mL] range with increased viability at lower doses [2-4 mg/mL] and decreasing cell viability above 6 mg/mL (Torres et al. 2022). In the same study, the authors demonstrated that the presence of terpenes, specifically b-caryophyllene, in hemp extraction matrices also impacted cell viability.

Neswell, a cannabis therapeutics company in Israel, demonstrated through the application of their in vitroneutrophil cell line that cannabis extracts have inherent immune response biodiversity, suggesting that the choice of a cannabis source should be based on its function rather than on its chemoprofile (https://www.neswell.net). Inflammatory cytokine levels in inflamed peripheral blood mononuclear cells (PB_MC) showed a 10-fold difference across hemp extract products containing unidentified terpenes in suppressing the inflammatory cytokine, TNFa (Torres et al. 2022). The influence of CBD concentration on inflammatory cytokine production was previously reported by Vuolo et al. (2015) and Jiang et al. (2022).

Materials & Methods

Chemicals and Products Tested

THC-free, 99% pure CBD and CBG isolates were purchased from Open Book extracts in North Carolina (openbookextracts.com). All other chemicals including erythromycin (EM), and growth media were obtained from Sigma-Aldrich (St. Louis MO). Specific reagents in the qPCR kits were assembled in-house at MatMaCorp Inc. (Lincoln NE).

Monitoring Cell Viability: OD600nm and plating

Individual frozen glycerin stocks of L. crispatus HM103 from BEI Resources Repository served as inoculum to streak on a sterile MRS agar plate and incubated anaerobically at 370C for 24-48 h until individual colony growth was observed. Single colonies were used to inoculate MRS broth and incubated for 24-48 h at 370C which served as the inoculum for exposure to test products. Exposed cultures and all control cultures were incubated at 370C for 48 h with OD600 readings taken at time zero, +24 h, and +48 h using disposable cuvettes in a standard spectrophotometer. The products were also plated onto MRS agar plates to evaluate inherent contaminants that could affect turbidity values.

Molecular Analysis by qPCR

DNA isolation from bacterial cultures was done using the MatMaCorp (Lincoln, NE) StickE Tissue DNA Isolation kit modified for bacteria as per manufacturer instructions. Briefly, a lysis buffer is applied to the sample followed by a heating step, and a binding buffer is added, thus allowing DNA from the solution to bind to the matrix of the StickE column. The column was washed prior to eluting the purified DNA. Per manufacturer instructions, 10 µL of isolated DNA was used as a template for genetic analysis in a Lacto-TM assay (MatMaCorp). The assay is a customized TaqMan-based detection assay that is conducted using a four-channel fluorescence detection platform, the Solas 8 (MatMaCorp). The assay was designed to detect the unique 16S-rRNA DNA sequence for L. crispatus. Briefly, the assay is a probe-based method that begins with hybridizing the custom-designed probes with their desired nucleic acid target found in the sample. Once hybridized, detection takes place from the fluorescently labeled primer. The target has been assigned a channelon the Solas 8 and is detected independently. 

Calling the Results

The calling algorithm uses first-order kinetics reaction properties (inflection point detection) in combinationwith a measure of the closeness of the signals associated with a specific target. Various indicators are tracked during the reactions to perform an on-the-fly analysis. The analysis is then consolidated by a measure of the similarity between the fluorescence signals at the end of the run. Aggregating values from the similarity measure, the end gain and the inflection point detection allow the Solas 8 software to make the call at the end of the run without having to compare a results library of known sample targets.

Figure 1: qPCR Findings

Results

Exposure of L. crispatus

Anaerobically grown cultures of L. crispatus were exposed to either CBD isolate or CBG isolate at each of two concentrations [5 mg/mL] and [10 mg/mL] with all appropriate controls. All treatment groups were evaluated by qPCR, turbidity at OD600, and plate counts.

Molecular Analysis via qPCR

These data show the specificity of the Solas8 testing for evaluating these products, as a molecular-level screening is not influenced by test product solubility, opacity, or non-specific contamination present in some of the tested products that can interfere with optical density measurements.

Growth Monitoring

Figure 2: Turbidity

Turbidity monitoring, albeit non-specific, confirmed the species-specific qPCR findings, that is no inhibition for the two cannabinoid isolates evaluated (Fig. 2).

Conclusions

In this limited in vitro study using a sentinel lactobacilli response, we have shown that 99% pure CBD and CBG isolates were not inhibitory at the two doses evaluated by complementary observations following turbidity, plating, and by qPCR. Limitations in this study prevent definitive conclusions regarding what individual or combination of cannabinoids or other cannabis secondary metabolites are inhibitory in vivo to dominant lactobacilli species in the reproductive tract. These limitations include commercial product testing without knowledge of excipients or impact on the bioavailability of any active cannabinoid ingredients. In addition, dose-response curves were not generated and exposure under micro-aerobic conditions was not carried out.

Cannabidiol’s potential as an antimicrobial agent may be limited by its extremely low solubility in water and a propensity to stick to spurious proteins limiting systemic distribution in the body as a therapeutic. Interpreting microbiome study findings to human health outcomes will require multi-disciplinary corresponding clinical data findings of disease diagnosis, processes, and treatment within populations. Nonetheless, this nascent translational research opportunity is vast with the promise of benefiting patient outcomes (Wensel et al. 2022).

Health Canada released a scientific review report on products containing cannabis, specifically containing 98% or greater CBD and less than 1% of THC (Health Canada 2022) while the FDA just concluded that there are no existing guidelines applicable for recommending safety and quality guidelines to manage risk for CBD products (U.S. FDA 2023). The Health Canada committee unanimously agreed that short-term use of CBD is safe at 20 mg per day up to a maximum dose of 200 mg per day and that packaging should include both dosing instructions and potential side effects. The Committee did not address the antimicrobial potential of CBD or CBG formulations or specifically vulvar or vaginally administered cannabinoids. There is clearly more basic physiological research needed on the impact of self-administration of CBD preparations based on the route of exposure.

References 

1. https://fda.gov/news-events/press-announcements/fda-concludes-existing-regulatory-frameworks-foods-and-supplements-are-not-appropriate-cannabidiol

Farha MA, El-Halfawy LM, Gale RT, MacNair CR, Carfrae LA, Zhang X, Jentsch NG, Magolan J, Brown ED (2020) Uncovering the hidden antibiotic potential of cannabis. ACS Infect Dis 6:338-346. 

Health Canada (2022). https://www.canada.ca/content/dam/hc-sc/documents/corporate/about-health-canada/public-engagement/external-advisory-bodies/health-products-containing-cannabis/report-cannabidiol-eng.pdf 

Hopkins AL (2008) Network pharmacology: the next paradigm in drug discovery. Nat Chem Biol 4(11):682-90.

Iseppi R, Brighenti V, Licata M, Lambertini A, Sabia C, Messi P, Pellati F, Benvenuti S (2019) Chemical characterization and evaluation of the antibacterial activity of essential oils from fibre-type Cannabis sativa L. (Hemp) Molecules 24:2302; doi:10.3390/molecules24122302.

Jiang Z, Jin S, Fan X, Cao K, Liu Y, Want X, Ma Y, Xiang L (2022) Cannabidiol inhibits inflammation induced by Cutibacterium acnes-derived extracellular vesicles via activation of CB2 receptor in keratinocytes. J Inflammation Res 15:4573-4583.

Orser CS (2022) Prevalence of Cannabinoid-containing Intimate Care Products Exposes Longstanding Unmet Need for Safety Data on Community Microbiota Exposure. https://cannabisindustryjournal.com/feature_article/intimate-care-products-with-cannabinoids-need-more-safety-data/

Torres AR, Caldwell VD, Morris S, Lyon R (2022) Human cells can be used to study cannabinoid dosage and inflammatory cytokine responses. Cannabis Sci & Tech 5(2) 38-45).

U.S. FDA (2023) https://www.fda.gov/news-events/press-announcements/fda-concludes-existing-regulatory-frameworks-foods-and-supplements-are-not-appropriate-cannabidiol

Vuolo F, Petronilho F, Sonai B, Ritter C, Hallak JE, Zuardi AW, Crippa JA, Dal-Pizzol F (2015) Mediators Inflamm 538670

Wensel CR, Salzberg SL, Sears CL (2022) Next-generation sequencing insights to advance clinical investigations of the microbiome. J Clin Invest 132(7):e154944. https://doi.org/10.1172/JCI154944.

Soapbox

How Do You Know You’re Right? qPCR vs. Plating

By Dr. Sherman Hom
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Cannabis testing to detect microbial contamination is complicated. It may not be rocket science, but it is life science, which means it’s a moving target, or at least, it should be, as we acquire more and more information about how the world we live in works. We are lucky to be able to carry out that examination in ever increasing detail. For instance, the science of genomics1 was born over 80 years ago, and just twenty years ago, genetics was still a black box. We’ve made tremendous progress since those early days, but we still have a long way to go, to be sure.

Much of that progress is due to our ability to build more accurate tools, a technological ladder, if you will, that raises our awareness, expertise, and knowledge to new levels. When a new process or technology appears, we compare it against accepted practice to create a new paradigm and make the necessary adjustments. But people have to be willing to change. In the cannabis industry, rapid change is a constant, first because that is the nature of a nascent industry, and second because in the absence of some universal and unimpeachable standard, it’s difficult to know who’s right. Especially when the old, reliable reference method (i.e. plating, which is basically growing microorganisms on the surface of a nutritional medium) is deeply flawed in its application to cannabis testing vs. molecular methods (i.e., quantitative polymerase chain reaction, or qPCR for short).

Dr. Sherman Hom, Director of Regulatory Affairs at Medicinal Genomics

Plating systems have been used faithfully for close to 130 years in the food industry, and has performed reasonably well.2 But cannabis isn’t food and can’t be tested as if it were. In fact, plating methods have a host of major disadvantages that only show up when they’re used to detect cannabis pathogens. They are, in no particular order:

  1. A single plating system can’t enumerate a group of microorganisms and/or detect specific bacterial and fungal pathogens. This is further complicated by the fact that better than 98% of the microbes in the world do not form colonies.3 And there is no ONE UNIVERSAL bacterial or fungal SELECTIVE agar plate that will allow the growth of all bacteria or all fungal strains. For example, the 5 genus species of fungal strains implicated in powderly mildew DO NOT plate at all.
  2. Cannabinoids, which can represent 10-30% of a cannabis flower’s weight, have been shown to have antibacterial activity.4 Antibiotics inhibit the growth of bacteria and in some cases kill it altogether. Salmonella species & shiga toxin producing coli (STEC) bacteria, in particular, are very sensitive to antibiotics, which leads to either a false negative result or lower total counts on plates vs. qPCR methods.
  3. Plating methods cannot detect bacterial and fungal endophytes that live a part or all of their life cycle inside a cannabis plant.5,6 Examples of endophytes are the Aspergillus pathogens (A. flavus, A. fumigatus, A. niger, and A. terreus). Methods to break open the plant cells to access these endophytes to prepare them for plating methods also lyse these microbial cells, thereby killing endophytic cells in the process. That’s why these endophytes will never form colonies, which leads to either false negative results or lower total counts on plates vs. qPCR methods.
  4. Selective plating media for molds, such as Dichloran Rose-Bengal Chloramphenicol (DRBC) actually reduces mold growth—especially Aspergillus—by as much as 5-fold.This delivers false negative results for this dangerous human pathogen. In other words, although the DRBC medium is typically used to reduce bacteria; it comes at the cost of missing 5-fold more yeast and molds than Potato Dextrose Agar (PDA) + Chloramphenicol or molecular methods. These observations were derived from study results of the AOAC emergency response validation.7
  5. Finally, we’ve recently identified four bacterial species, which are human pathogens associated with cannabis that do not grow at the plating system incubation temperature typically used.8 They are Aeromonas hydrophila, Pantoea agglomerans, Yersinia enterocolitica, and Rahnella aquatilis. This lowers total counts on plates qPCR methods.

So why is plating still so popular? Better yet, why is it still the recommended method for many state regulators? Beats me. But I can hazard a couple of guesses.

A yeast and mold plate test

First, research on cannabis has been restricted for the better part of the last 70 years, and it’s impossible to construct a body of scientific knowledge by keeping everyone in the dark. Ten years ago, as one of the first government-employed scientists to study cannabis, I was tapped to start the first cannabis testing lab at the New Jersey Dept. of Health and we had to build it from ground zero. Nobody knew anything about cannabis then.

Second, because of a shortage of cannabis-trained experts, members of many regulatory bodies come from the food industry—where they’ve used plating almost exclusively. So, when it comes time to draft cannabis microbial testing regulations, plating is the default method. After all, it worked for them before and they’re comfortable with recommending it for their state’s cannabis regulations.

Finally, there’s a certain amount of discomfort in not being right. Going into this completely new area—remember, the legal cannabis industry didn’t even exist 10 years ago—we human beings like to have a little certainty to fall back on. The trouble is, falling back on what we did before stifles badly needed progress. This is a case where, if you’re comfortable with your old methods and you’re sure of your results, you’re probably wrong.

So let’s accept the fact that we’re all in this uncharted territory together. We don’t yet know everything about cannabis we need to know, but we do know some things, and we already have some pretty good tools, based on real science, that happen to work really well. Let’s use them to help light our way.

References

  1. J. Weissenbach. The rise of genomics. Comptes Rendu Biologies, 339 (7-8), 231-239 (2016).
  2. R. Koch. 1882. Die Aetiologie der Tuberculose.  Berliner Klinische Wochenschrift, 19, 221-230 (1882). 
  3. W. Wade. Unculturable bacteria—the uncharacterized organisms that cause oral infections. Journal of the Royal Society of Medicine, 95(2), 91-93 (2002).
  4. J.A. Karas, L.J.M. Wong, O.K.A. Paulin, A. C. Mazeh, M.H. Hussein, J. Li, and T. Vekov. Antibiotics, 9(7), 406 (2020).
  5. M. Taghinasab and S. Jabaji, Cannabis microbiome and the role of endophytes in modulating the production of secondary metabolites: an overview. Microorganisms 2020, 8, 355, 1-16 (2020).
  6. P. Kusari, S. Kusari, M. Spiteller and O. Kayser, Endophytic fungi harbored in Cannabis sativa L.: diversity and potential as biocontrol agents against host plant-specific phytopathogens. Fungal Diversity 60, 137–151 (2013).
  7. K. McKernan, Y. Helbert, L. Kane, N. Houde, L. Zhang, S. McLaughlin, Whole genome sequencing of colonies derived from cannabis flowers & the impact of media selection on benchmarking total yeast & mold detection tools,  https://f1000research.com/articles/10-624 (2021).
  8. K. McKernan, Y. Helbert, L. Kane, L. Zhang, N. Houde, A. Bennett, J. Silva, H. Ebling, and S. McLaughlin, Pathogenic Enterobacteriaceae require multiple culture temperatures for detection in Cannabis sativa L. OSF Preprints, https://osf.io/j3msk/, (2022)

Medicinal Genomics Salmonella and STEC E. coli Multiplex Assay Certified by AOAC

By Cannabis Industry Journal Staff
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Medicinal Genomics announced today that they have received AOAC International certification for their PathoSEEK® Salmonella and STEC E. coli multiplex assay. In combination with their SenSATIVAx® extraction kits, labs can simultaneously detect Salmonella spp. and STEC E. coli with a single qPCR reaction for flower, concentrates and infused chocolates using the Agilent AriaMx and the BioRad CFx-96 instruments.

The certification came after the multiplex assay was validated according to the AOAC Performance Tested Method Program. According to the press release, the PathoSEEK platform now has more cannabis matrices accredited for Aspergillus, Salmonella, and STEC E. coli than any other product out on the market, according to their press release.

The PathoSEEK microbiological testing platform uses a qPCR assay and internal plant DNA controls for reactions. The two-step protocol verifies performance while detecting microbes, which allegedly helps minimize false negative results from human error or failing conditions.

“AOAC’s validation of our Salmonella/STEC E. coli assay across the various cannabis matrices is further proof of our platform’s robustness and versatility,” says Dr. Sherman Hom, director of regulatory affairs at Medicinal Genomics. “We are excited that our PathoSEEK® platform is moving in concert with the FDA’s new blueprint to improve food safety by modernizing the regulatory framework, while leveraging the use of proven molecular tools to accelerate predictive capabilities, enhance prevention, and enhance our ability to swiftly adapt to pathogen outbreaks that could impact consumer safety.”

Leaders in Cannabis Testing – Part 1: A Q&A with Milan Patel, CEO and Co-Founder of PathogenDx

By Aaron Green
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In this “Leaders in Cannabis Testing” series of articles, Green interviews cannabis testing laboratories and technology providers that are bringing unique perspectives to the industry. Particular attention is focused on how these businesses integrate innovative practices and technologies to navigate a rapidly changing landscape of regulatory constraints and B2B demand.

PathogenDx is an Arizona-based provider of microbial testing technologies. Since their inception in 2014, they have broadened their reach to 26 states in the US. In addition to cannabis product testing, PathogenDx also provides technologies for food safety testing, environmental testing and recently started offering human diagnostics testing to support COVID-19 response efforts.

We interviewed Milan Patel, CEO and co-founder of PathogenDx. Milan founded PathogenDx as a spin-off from one of his investments in a clinical diagnostics company testing for genetic markers in transplant organs. Prior to PathogenDx, Milan worked in finance and marketing at Intel and later served as CFO at Acentia (now Maximus Federal).

Aaron Green: What’s the history of PathogenDx?

Milan Patel: PathogenDx was effectively a spin-off of a clinical diagnostics company that my partner Dr. Mike Hogan, the inventor of the technology, had founded when he was a professor at the University of Arizona, but previously at Baylor Medical College back in 2002. I had invested in the company back then and I had realized that his technology had a broad and wide sweeping impact for testing – not just for pathogens in cannabis specifically, but also for pathogens in food, agriculture, water and even human diagnostics. In the last 14 months, this became very personal for every single person on the planet having been impacted by SARS-CoV-2, the viral pathogen causing Covid-19. The genesis of the company was just this, that human health, food and agricultural supply, and the environment has and will continue to be targeted by bacterial, fungal and viral pathogens impacting the safety and health of each human on the planet.

We founded PathogenDx and we pivoted the company from its original human organ transplant genetics market scope into the bigger markets; we felt the original focus was too niche for a technology with this much potential. We licensed the technology, and we repurposed it into primarily cannabis. We felt that achieving commercial success and use in the hands of cannabis testing labs at the state level where cannabis was first regulated was the most logical next step. Ultimately, our goal was and is to move into markets that are approved at the federal regulatory side of the spectrum, and that is where we are now.

Green: What year was that?

Milan Patel, CEO and Co-Founder of PathogenDx
Photo credit: Michael Chansley

Patel: 2014.

Green: So, PathogenDx started in cannabis testing?

Patel: Yes, we started in cannabis testing. We now have over 100 labs that are using the technology. There is a specific need in cannabis when you’re looking at contamination or infection.

In the case of contamination on cannabis, you must look for bacterial and fungal organisms that make it unsafe, such as E. coli, or Salmonella or Aspergillus pathogens. We’re familiar with recent issues like the romaine lettuce foodborne illness outbreaks at Chipotle. In the case of fungal organisms such as Aspergillus, if you smoke or consume contaminated cannabis, it could have a huge impact on your health. Cannabis regulators realized that to ensure public health and safety there was more than just one pathogen – there were half a dozen of these bugs, at a minimum, that could be harmful to you.

The beauty of our technology, using a Microarray is that we can do what is called a multiplex test, which means you’re able to test for all bacterial and fungal pathogens in a single test, as opposed to the old “Adam Smith” model, which tests each pathogen on a one-by-one basis. The traditional approach is costly, time consuming and cumbersome. Cannabis is such a high value crop and producers need to get the answer quickly. Our tests can give a result in six hours on the same day, as opposed to the two or three days that it takes for these other approved methods on the market.

Green: What is your business model? Is there equipment in addition to consumables?

Patel: Our business model is the classic razor blade model. What that means is we sell equipment as well as the consumables – the testing kits themselves.

The PathogenDx technology uses standard, off-the-shelf lab equipment that you can find anywhere. We didn’t want to make the equipment proprietary so that a lab has to buy a specific OEM branded product. They can use almost any equipment that’s available commercially. We wanted to make sure that labs are only paying a fraction of the cost to get our equipment, as opposed to using other vendors. Secondly, the platform is open-ended, meaning it’s highly flexible to work with the volumes that different cannabis labs see daily, from high to low.

One equipment set can process many different types of testing kits. There are kits for regulated testing required by states, as well as required environmental contamination.

Green: Do you provide any in-house or reference lab testing?

Patel: We do. We have a CLIA lab for clinical testing. We did this about a year ago when we started doing COVID testing.

We don’t do any kind of in-house reference testing for cannabis, though we do use specific reference materials or standards from Emerald Scientific, for example, or from NCI. Our platform is all externally third-party reference lab tested whether it’s validated by our external cannabis lab customers or an independent lab. We want our customers to make sure that the actual test works in their own hands, in their own facility by their own people, as opposed to just shrugging our shoulders and saying, “hey, we’ve done it ourselves, believe us.” That’s the difference.

Green: Can you explain the difference between qPCR and endpoint PCR?

Patel: The difference between PathogenDx’s Microarray is it uses endpoint PCR versus qPCR (quantitative real time PCR). Effectively, our test doesn’t need to be enriched. Endpoint PCR delivers a higher level of accuracy, because when it goes to amplify that target DNA, whether it’s E. coli, Salmonella or Aspergillus pieces, it uses all the primer reagent to its endpoint. So, it amplifies every single piece of an E. Coli (for example) in that sample until the primer is fully consumed. In the case of qPCR, it basically reaches a threshold and then the reaction stops. That’s the difference which results in a much greater level of accuracy. This provides almost 10 times greater sensitivity to identify the pathogen in that sample.

The second thing is that we have separated out how the amplified sample hybridizes to the probe. In the case of our assay, we have a microarray with a well in it and we printed the actual probe that has the sequence of E. coli in there, now driving 100% specificity. Whereas in the qPCR, the reaction is not only amplifying, but it’s also basically working with the probe. So, in that way, we have a higher level of efficiency in terms of specificity. You get a definite answer exactly in terms of the organism you’re looking for.

In terms of an analogy, let’s take a zip code for example which has the extra four digits at the end of it.  In the case of endpoint PCR, we have nine digits. We have our primer probes which represent the standard five digits of a zip code, and the physical location of the probe itself in the well which serves as the extra four digits of that zip code. The analyte must match both primary and secondary parts of the nine-digit zip code for it to lock in, like a key and a lock. And that’s the way our technology works in a nutshell.

Endpoint PCR is completely different. It drives higher levels of accuracy and specificity while reducing the turnaround time compared to qPCR – down to six hours from sample to result. In qPCR, you must enrich the sample for 24 to 48 hours, depending on bacteria or fungus, and then amplification and PCR analysis can be done in one to three hours. The accuracies and the turnaround times are the major differences between the endpoint PCR and qPCR.

Green: If I understand correctly, it’s a printed microarray in the well plate?

Patel: That’s correct. It’s a 96-well plate, and in each well, you’ve now printed all the probes for all targets in a single well. So, you’re not running more than one well per target, or per organism like you are for qPCR. You’re running just one well for all organisms. With our well plates, you’re consuming fewer wells and our patented foil-cover, you only use the wells you need. The unused wells in the well plate can be used in future tests, saving on costs and labor.

Green: Do you have any other differentiating IP?

The PathogenDx Microarray

Patel: The multiplex is the core IP. The way we process the raw sample, whether it’s flower or non-flower, without the need for enrichment is another part of the core IP. We do triplicate probes in each well for E. Coli, triplicate probes for Salmonella, etc., so there are three probes per targeted organism in each of the wells. We’re triple checking that you’re definitively identifying that bug at the end of the day. This is the cornerstone of our technology.

We were just approved by the State of New York, and the New York Department of Health has 13 different organisms for testing on cannabis. Think about it: one of the most rigorous testing requirements at a state level – maybe even at a federal level – and we just got approved for that. If you had to do 13 organisms separately, whether it’s plate culture or qPCR, it would become super expensive and very difficult. It would break the very backs of every testing lab to do that. That’s where the multiplexing becomes tremendously valuable because what you’re doing is leveraging the ability to do everything as a single test and single reaction.

Green: You mentioned New York. What other geographies are you active in?

Patel: We’re active in 26 different states including the major cannabis players: Florida, Nevada, California, Arizona, Michigan, New York, Oklahoma, Colorado and Washington – and we’re also in Canada. We’re currently working to enter other markets, but it all comes down to navigating the regulatory process and getting approval.

We’re not active currently in other international markets yet. We’re currently going through the AOAC approval process for our technology and I’m happy to say that we’re close to getting that in the next couple of months. Beyond that, I think we’ll scale more internationally.

I am delighted to say that we also got FDA EUA federal level authorization of our technology which drives significant credibility and confidence for the use of the technology. About a year ago, we made a conscious choice to make this technology federally acceptable by going into the COVID testing market. We got the FDA EUA back on April 20, ironically. That vote of confidence by the FDA means that our technology is capable of human testing. That has helped to create some runway in terms of getting federalized with both the FDA and the USDA, and certification by AOAC for our different tests.

Green: Was that COVID-19 EUA for clinical diagnostics or surveillance?

Patel: It was for clinical diagnostics, so it’s an actual human diagnostic test.

Green: Last couple of questions here. Once you find something as a cannabis operator, whether its bacteria or fungus, what can you do?

Patel: There are many services that are tied into our ecosystem. For example, we work with Willow Industries, who does remediation.

There’s been a lot of criticism around DNA based technology. It doesn’t matter if it’s qPCR or endpoint PCR. They say, “well, you’re also including dead organisms, dead DNA.” We do have a component of separating live versus dead DNA with a biomechanical process, using an enzyme that we’ve created, and it’s available commercially. Labs can test for whether a pathogen is living or dead and, in many cases, when they find it, they can partner with remediation companies to help address the issue at the grower level.

Another product we offer is an EnviroX test, which is an environmental test of air and surfaces. These have 50 pathogens in a single well. Think about this: these are all the bad actors that typically grow where soil is – the human pathogens, plant pathogens, powdery mildew, Botrytis, Fusarium – these are very problematic for the thousands of growers out there. The idea is to help them with screening technology before samples are pulled off the canopy and go to a regulated lab. We can help the growers isolate where that contamination is in that facility, then the remediation companies can come in, and help them save their crop and avoid economic losses.

Green: What are you most interested in learning about?

Patel: I would prefer that the cannabis industry not go through the same mistakes other industries have gone through. Cannabis started as a cottage industry. It’s obviously doubled every year, and as it gets scaled, the big corporations come in. Sophistication, standards, maturity all help in legitimacy of a business and image of an industry. At the end of the day, we have an opportunity to learn from other industries to really leapfrog and not have to go through the same mistakes. That’s one of the things that’s important to me. I’m very passionate about it.

One thing that I’ll leave you with is this: we’re dealing with more bugs in cannabis than the food industry. The food industry is only dealing with two to four bugs and look at the number of recalls they are navigating – and this is a multi-billion-dollar industry. Cannabis is still a fraction of that and we’re dealing with more bugs. We want to look ahead and avoid these recalls. How do you avoid some of the challenges around antimicrobial resistance and antibiotic resistance? We don’t want to be going down that road if we can avoid it and that’s sort of a personal mission for myself and the company.

Cannabis itself is so powerful, both medicinally as well as recreationally, and it can be beneficial for both consumers and industry image if we do the right things, and avoid future disasters, like the vaping crisis we went through 18 months ago because of bad GMPs. We must learn from those industries. We’re trying to make it better for the right reasons and that’s what’s important to me.

Green: Okay, great. That concludes the interview. Thank you, Milan.

Patel: Thank you for allowing me to share my thoughts and your time, Aaron.

Cannabis Scientists and Labs Can Help with National COVID-19 Research Volunteer Database

By Aaron Green
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Harvard Neuroscientist, Michael Wells, and a team of volunteer scientists from endCoronavirus.org have created and stocked a national database of scientists and researchers ready, willing and able to help with response efforts for COVID-19. At the time of this writing, more than 8,000 scientists have registered from all 50+ states.

It all started with a Tweet on March 18th. 

“I really wanted an outlet for me, like someone like me, to be able to help out in this fight,” Wells said in a Harvard Crimson interview. “I knew I was, by far, not the only one who felt this way. And so what happened was, on the walk home from work that day from the lab, I thought, ‘Hey, I should try to organize something here in Boston so I could potentially be a part of a group that makes themselves available to health department officials or county officials.’”

Volunteers are made up of a mix of laboratory scientists, data scientists, software engineers, medical writers, CEOs and epidemiologists – from academic research institutes, national labs and private industry. Many state and local government agencies and organizations have already accessed the list for reference, including FEMA.

PCR testing is used in a wide variety of applications
Image: Peggy Greb, USDA

Members of the cannabis industry can help to combat COVID-19. “The cannabis industry relies on specialized laboratories that routinely perform qPCR-based microbial tests,” says Wells. “As a result, these labs have basic skill sets and facilities required to participate in community COVID-19 testing.” Quantitative Polymerase chain reaction (qPCR), is a common technique for determining if there are microbial contaminants in flower, concentrates and infused products.

Some cannabis industry leaders have already taken to the call. “With the trend in legalization, the cannabis industry has built an excess testing capacity in anticipation of an increase in volumes,” says David Winternheimer, PhD, CEO of Pacific Star Labs, a Los Angeles-based cannabis research organization with an ISO-accredited testing laboratory. “As an essential industry, cannabis companies are open to helping the wider population in a crisis like this, and testing could easily be adopted in labs with excess microbial testing capacity.”

Michael Wells and his band of volunteers are asking to help get the word out to other scientists who would like to sign-up at https://covid19sci.org and for anyone to help share the database link with any relevant person in government or health services. “Right now, it is all hands on deck. We need every lab, facility, and pair of skilled hands to be deployed in this fight against the most dangerous pathogen our species has experienced at this scale in our lifetimes.”

 

endCoronavirus.org is a volunteer organization with over 6,000 members built and maintained by the New England Complex Systems Institute (NECSI) and its collaborators. The group specializes in networks, agent-based modeling, multi-scale analysis and complex systems and provides expert information on how to stop COVID-19.

The COVID-19 National Scientist Volunteer Database is a database of over 8,000 scientists from all 50 states, DC, Puerto Rico, and Guam who are eager to volunteer our time, expertise, equipment, and consumables to help you respond to the COVID-19 crisis. They have aggregated our contact information, locations, and skills sets into this easy to use centralized database. Their members include experts in scientific testing, bioinformatics, and data management, as well as key contacts willing to donate lab space and testing supplies.

3 Essential Components of Microbial Safety Testing

By Heather Ebling
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Microbial contamination on cannabis products represents one of the most significant threats to cannabis consumers, particularly immunocompromised patients who are at risk of developing harmful and potentially fatal infections.

As a result, regulatory bodies in the United States and Canada mandate testing cannabis products for certain microbes. The two most popular methods for microbial safety testing in the cannabis industry are culture-based testing and quantitative polymerase chain reaction (qPCR).

When considering patient safety, labs should choose a method that provides an accurate account of what is living on the sample and can specifically target the most harmful microbes, regardless of the matrix.

1. The Method’s Results Must Accurately Reflect the Microbial Population on the Sample

The main objective of any microbial safety test is to give the operator an indication of the microbial population present on the sample.

Figure 1: MA data collected directly from plant material before and after culture on 3M petrifilm and culture-based platforms.

Culture-based methods measure contamination by observing how many organisms grow in a given medium. However, not all microbial organisms grow at the same rate. In some cases, certain organisms will out-compete others and as a result, the population in a post-culture environment is radically different than what was on the original sample.

One study analyzed fifteen medicinal cannabis samples using two commercially available culture-based methods. To enumerate and differentiate bacteria and fungi present before and after growth on culture-based media, all samples were further subjected to next-generation sequencing (NGS) and metagenomic analyses (MA). Figure 1 illustrates MA data collected directly from plant material before and after culture on 3M petrifilm and culture-based platforms.

The results demonstrate substantial shifts in bacterial and fungal growth after culturing on the 3M petrifilm and culture-based platforms. Thus, the final composition of microbes after culturing is markedly different from the starting sample. Most concerning is the frequent identification of bacterial species in systems designed for the exclusive quantification of yeast and mold, as quantified by elevated total aerobic count (TAC) Cq values after culture in the total yeast and mold (TYM) medium. The presence of bacterial colonies on TYM growth plates or cartridges may falsely increase the rejection rate of cannabis samples for fungal contamination. These observations call into question the specificity claims of these platforms.

The Live Dead Problem

Figure 2: The enzyme is instantaneously inactivated when lysis buffer is added

One of the common objections to using qPCR for microbial safety testing is the fact that the method does not distinguish between live and dead DNA. PCR primers and probes will amplify any DNA in the sample that matches the target sequence, regardless of viability. Critics claim that this can lead to false positives because DNA from non-viable organisms can inflate results. This is often called the Live-Dead problem. However, scientists have developed multiple solutions to this problem. Most recently, Medicinal Genomics developed the Grim Reefer Free DNA Removal Kit, which eliminates free DNA contained in a sample by simply adding an enzyme and buffer and incubating for 10 minutes. The enzyme is instantaneously inactivated when lysis buffer is added, which prevents the Grim Reefer Enzyme from eliminating DNA when the viable cells are lysed (see Figure 2).

2. Method Must Be Able to Detect Specific Harmful Species 

Toxic Aspergillus spp., which is responsible for at least one confirmed death of a cannabis patient, grows poorly in culture mediums and is severely underreported by current culture-based platforms. And even when Aspergillus does grow in culture, there is a certain non-pathogenic Aspergillus species that look remarkably similar to their pathogenic cousins, making it difficult to speciate using visual identification alone.

Figure 3: The team spiked a known amount of live E. coli into three different environments

Conversely, qPCR assays, such as the PathoSEEK, are designed to target DNA sequences that are unique to pathogenic Aspergillus species, and they can be run using standard qPCR instruments such as the Agilent AriaMx. The primers are so specific that a single DNA base difference in the sequence can determine whether binding occurs. This specificity reduces the frequency of false positives in pathogen detection, a frequent problem with culture-based cannabis testing methods.

Additionally, Medicinal Genomics has developed a multiplex assay that can detect the four pathogenic species of Aspergillus (A. flavus, A. fumigatus, A. niger, and A. terreus) in a single reaction.

3. The Method Must Work on Multiple Matrices 

Figure 4: The team also placed TSB without any E. coli onto a petrifilm to serve as a control.

Marijuana infused products (MIPs) are a very diverse class of matrices that behave very differently than cannabis flowers. Gummy bears, chocolates, oils and tinctures all present different challenges to culture-based techniques as the sugars and carbohydrates can radically alter the carbon sources available for growth. To assess the impact of MIPs on colony-forming units per gram of sample (CFU/g) enumeration, The Medicinal Genomics team spiked a known amount of live E. coli into three different environments: tryptic soy broth (TSB), hemp oil and hard candy. The team then homogenized the samples, pipetted amounts from each onto 3M™ Petrifilm E. coli / Coliform Count (EC) Plates, and incubated for 96 hours. The team also placed TSB without any E. coli onto a petrifilm to serve as a control. Figures 3 and 4 show the results in 24-hour intervals.

Table 1: DNA was spiked into various MIPs

This implies the MIPs are interfering with the reporter assay on the films or that the MIPs are antiseptic in nature.

Many MIPs use citric acid as a flavoring ingredient which may interfere with 3M reporter chemistry. In contrast, the qPCR signal from the Agilent AriaMx was constant, implying there is microbial contamination present on the films, but the colony formation or reporting is inhibited.

Table 3: SenSATIVAx DNA extraction can successfully lyse the cells of the microbes
Table 2: Different numbers of DNA copies spiked into chocolate

This is not an issue with DNA-based methods, so long as the DNA extraction method has been validated on these matrices. For example, the SenSATIVAx DNA extraction method is efficient in different matrices, DNA was spiked into various MIPs as shown in Table 1, and at different numbers of DNA copies into chocolate (Table 2). The SenSATIVAx DNA extraction kit successfully captures the varying levels of DNA, and the PathoSEEK detection assay can successfully detect that range of DNA. Table 3 demonstrates that SenSATIVAx DNA extraction can successfully lyse the cells of the microbes that may be present on cannabis for a variety of organisms spiked onto cannabis flower samples.