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Microorganisms in Cannabis Should We Be Concerned

Uncategorized May 16, 2023


Cannabis has become increasingly popular in the healthcare industry due to its potential therapeutic benefits. Patients with compromised health often use it to alleviate symptoms of various medical conditions. However, recent studies have shown that cannabis materials used in healthcare settings may contain dangerous microorganisms that can cause opportunistic infections. This is especially concerning for patients with compromised immune systems who are more vulnerable to these infections. In this blog post, we will explore the potential dangers of microorganisms in cannabis materials and their impact on healthcare settings.

Australian Contemporary News:

A recent News article in the Sydney Morning Herald highlights the increasing use of medicinal cannabis in Australia, with over 1 million patients being prescribed the drug since its legalization in 2016. In 2022 alone, doctors prescribed medicinal cannabis to 316,879 new patients, a significant increase from previous years. The most common conditions treated with medicinal cannabis are chronic pain, anxiety, sleep disorders, and cancer pain management.

The acceptance of medicinal cannabis is growing, and some states in Australia are reviewing drug-driving laws to treat it like other prescription drugs. Specialist pharmacies have emerged to dispense medicines derived from cannabis treatments, primarily containing CBD or THC compounds.

However, there is still limited evidence on the effectiveness of medicinal cannabis, and opinions about it vary widely. Many GPs feel uncomfortable discussing it with patients due to a lack of knowledge and education on the subject. The survey mentioned in the article indicates that while there is growing support for medical cannabis, there is a need for more research and education for healthcare professionals.

The cost of medicinal cannabis is a concern for patients, as it is not subsidized by the government's Pharmaceutical Benefits Scheme. Aimee Sloan hopes for increased government support and accessibility to CBD oil for other families with autistic children.

Overall, the article highlights the rising acceptance and use of medicinal cannabis in Australia, the need for further research and education, and the financial challenges associated with accessing the treatment.


But inhalation of fine particles is not without risk.  A recent paper looked at this problem:

Inhalation of bioactive cannabis plant material cooked in a vaporizer, aerosolized, and breathed is very worrying. High temperatures destroy microorganisms like bacteria and fungi, but time and temperature are needed. It is unclear if a commercial vaporizer used in therapeutic settings will considerably reduce cannabis plant material bacteria burdens.

To test the hypothesis, our team utilised a commercial vaporizer to test NIDA-supplied bulk cannabis plant material. Initial method development tests utilising a cannabis placebo spiked with Escherichia coli optimised culture and recovery parameters. Heat was applied for 30 or 70 seconds at 190°C. Plating on growth media and counting aerobic microbial and yeast and mould counts assessed microbial growth after heating or not.

The results showed that while heating did reduce microbial counts, these reductions were not statistically significant, suggesting that standard vaporization parameters of 70 seconds at 190°C may not eliminate the existing microbial bioburden, including opportunistic pathogens. This raises concerns about the safety of using cannabis materials in healthcare settings.

During DNA sequence analysis, Enterobacteriaceae, Staphylococcus, Pseudomonas, and Aspergillus were found in cultivated organisms. These microorganisms are known to cause various infections in humans, especially those with weakened immune systems. This indicates that the use of cannabis materials may not be as safe as once thought.

As healthcare providers, it is important to be aware of the potential risks involved in using cannabis materials in healthcare settings. Patients with weakened immune systems should avoid using improperly sterilized cannabis materials to prevent harmful infections.

Hypersensitivity Pneumonitis Caused by Recreational Marijuana Use: A Case Study:

Hypersensitivity pneumonitis, also known as extrinsic allergic alveolitis, is a lung disease caused by the inhalation of foreign matter such as pollen, molds, chemicals, and smoke. HP leads to inflammation and can even progress to fibrosis in chronic cases. In recent years, recreational marijuana use has become more widespread, leading to an increase in cases of HP caused by contaminated cannabis. In this blog post, we will discuss a patient case in which HP was diagnosed after using recreational marijuana and effective treatment with corticosteroids.

Our patient, a 31-year-old female, presented with shortness of breath, cough, and chest tightness. Upon investigation, the patient's chest x-ray showed significant interstitial markings indicative of an inflammatory process in the lungs. The patient reported smoking marijuana frequently and obtaining it through an illicit street business. Based on the symptoms and exposure history, we suspected HP and initiated a steroid regimen of prednisone 40mg/day. The patient’s chest x-ray had complete resolution after only one day, which is a remarkable speed of healing in a lung disease such as HP.

Recreational cannabis obtained through illicit sources is more likely to contain impurities such as molds and pesticides, a potential insult to the lungs. Inhalation of these impurities can cause damage to the lung parenchymal and interstitial tissue leading to an immune response by the body. As recreational cannabis use increases, clinicians need to be aware of the potential risk of HP in patients who frequently use recreational marijuana obtained from unreliable sources.

Patients with HP may present with a variety of symptoms such as cough, fever, and shortness of breath. As the disease progresses, it may cause chronic cough, weight loss, and fibrosis. HP should be differentiated from other lung diseases such as chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD), which may have similar symptoms. High-resolution CT scan and bronchoscopy with biopsy may be helpful in confirming the diagnosis.

Corticosteroids are the primary mode of treatment for HP. However, patients with chronic, fibrotic HP may benefit from immunosuppressants and antifibrotic agents such as pirfenidone, nintedanib, and mycophenolate mofetil. Oxygen therapy and pulmonary rehabilitation may also help improve symptoms and quality of life for patients with advanced stages of the disease.


While cannabis has shown potential therapeutic benefits, there are potential risks involved in using cannabis materials in healthcare settings. Microorganisms on cannabis materials used in healthcare settings may cause opportunistic infections, particularly in patients with weakened immune systems. It is important for healthcare providers to be aware of these risks and take the necessary precautions to prevent harmful infections. As the use of cannabis materials in healthcare settings becomes more common, further research is needed to ensure their safety for all patients.

Although recreational marijuana use has become increasingly popular, it has also led to an increase in cases of HP caused by contaminated cannabis. Clinicians need to be aware of the potential risk of HP in patients who frequently use marijuana obtained from unreliable sources. HP should be differentiated from other lung diseases and confirmed with high-resolution CT scans and bronchoscopy. Corticosteroids are the primary mode of treatment; however, patients with chronic, fibrotic HP may benefit from immunosuppressants and antifibrotic agents. The awareness of this potential risk can help in the early diagnosis and prompt treatment of HP, thereby reducing morbidity and mortality.

Of course, not consuming cannabis is also an obvious choice as well. But each to their own.


Sopovski DS, Han J, Stevens-Riley M, Wang Q, Erickson BD, Oktem B, Vanlandingham M, Taylor CL, Foley SL. Investigation of microorganisms in cannabis after heating in a commercial vaporizer. Front Cell Infect Microbiol. 2023 Jan 13;12:1051272. doi: 10.3389/fcimb.2022.1051272. PMID: 36710966; PMCID: PMC9880168. 

Luke ND, Vefali B, Chow P, Miller R. Acute Recreational Cannabis-Induced Hypersensitivity Pneumonitis: A Case Report. Cureus. 2023 Apr 8;15(4):e37312. doi: 10.7759/cureus.37312. PMID: 37181992; PMCID: PMC10166773.



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