CBD, Superbug Killer?

Almost unnoticed among the multitude of presentations made during ASM Microbe—the annual meeting of the American Society for Microbiology, which ended Monday in San Francisco—was research presented Sunday out of Australia indicating the “surprising” effectiveness of cannabis as a powerful antibiotic.

Mark Blaskovich, senior research chemist at the University of Queensland’s Institute for Molecular Bioscience’s Centre for Superbug Solutions, presented work that assessed the “anti-bacterial properties in cannabidiol, or CBD, a non-psychoactive compound naturally derived from marijuana,” per Courthouse News. “Researchers believe CBD could be used to treat common strains of Staphyloccocus aureus and Streptococcus pneumonia that are resistant to many drugs currently on the market.”

Lab work for the study, done in collaboration with Perth-based
biopharmaceutical company Botanix Pharmaceuticals, used synthetic CBD rather than plant extracts to avoid impurities. “In addition to expanding the number of known bacteria CBD can kill, [researchers] tested how long CBD’s effectiveness lasted against superbugs, finding that many bacteria were slow or unable to adapt new resistance—a phenomena that requires further research to understand,” added Courthouse News.

“We don’t know how it works and that’s the interesting thing that we need to do further investigations into,” Blaskovich said in an interview. “It might be unique mechanism of action or it might be one that is used by other antibiotics and we just haven’t identified it.”

As promising as this research is Blaskovich said more is required before conclusive claims can be made that CBD kills superbugs. “This is a limited data,” he cautioned. “There’s no evidence yet that it works in humans and particularly for serious infections that are systemic or internal as opposed to things on the skin.”

Presentation Abstract:
Author Block: M. A. T. Blaskovich1, A. Kavanagh1, S. Ramu1, S. Levy2, M. Callahan2, M. Thurn2; 1The Univ. of Queensland, Brisbane, QLD, Australia, 2Botanix Pharmaceuticals Ltd, Perth WA, Australia.

Disclosure Block: M.A.T. Blaskovich: C. Consultant; Self; Consultant to several companies conducting antibiotic research. E. Grant Investigator; Self; Investigator on a number of grants funding antibiotic research. J. Scientific Advisor (Review Panel or Advisory Committee); Self; Member, Strategic Advisory Board, Compounds Australia. A. Kavanagh: None. S. Ramu: None. S. Levy: N. Pharmaceutical Industry Employee; Self; CMO of Botanix Pharmaceuticals Ltd. M. Callahan: N. Pharmaceutical Industry Employee; Self; CEO of Botanix Pharmaceuticals Ltd. M. Thurn: N. Pharmaceutical Industry Employee; Self; COO of Botanix Pharmaceuticals Ltd.

Background: Infections caused by drug-resistant Gram-positive bacteria affect millions of people and cause tens of thousands of deaths in North America alone. New antimicrobial agents are urgently needed, particularly novel structural classes with new mechanisms of action that can overcome resistant strains. Cannabidiol, the main non-psychoactive component of cannabis, has found increasing attention for a range of medical conditions, including epilepsy and inflammation. Here, we assess the antimicrobial activity of synthetically produced cannabidiol, free from isolation-dependent impurities that may confound biological testing results obtained with plant extracts.

Material/methods: Cannabidiol was tested in a suite of standard antimicrobial assays, starting with broth microdilution assays against a range of aerobic and anaerobic Gram-positive bacteria. Time-kill, resistance induction, and biofilm disruption experiments were also conducted, along with assessment of in vivo activity against MRSA in a murine neutropenic thigh infection model.

Results: Cannabidiol was remarkably effective at killing a range of Gram-positive (but not Gram-negative) bacteria, with broth microdilution MICs similar to clinical antibiotics such as vancomycin and daptomycin. Notably, activity was retained against-resistant strains of S. aureus (MRSA, VISA, VRSA), Streptococcus pneumoniae (MDR) and E. faecalis (VRE). Cannabidiol was bactericidal, showed low levels of propensity to induce resistance, and was active against MRSA biofilms.

Conclusion: Cannabidiol possesses surprisingly effective activity as an antibiotic, comparable to widely used antibiotics for Gram positive infections such as vancomycin and daptomycin, but with retention of activity against bacteria that have become resistant to these drugs. Given cannabidiol’s documented anti-inflammatory effects, extensive safety data in humans, and potential for oral delivery, it is a promising new antibiotic. The combination of inherent antimicrobial activity and potential to reduce damage caused by the inflammatory response to infections is particularly attractive.

Photo courtesy of Dr Graham Beards at en.wikipedia.