Can Cannabidiol Fight Drug-Resistant Gram-Positive Bacteria?

Infections that are caused by drug-resistant gram-positive bacteria are a serious threat as they affect millions of people and cause thousands of deaths in United States. In order to combat this urgent threat, new antimicrobials are desperately needed that have novel structural classes and unique mechanisms of action that can fight against highly resistant strains.

An encouraging step in the right direction, a team of investigators from Australia hypothesize that cannabidiol, which is the main non-psychoactive component of cannabis, could be an option for the fight against these resistant pathogens, as it has attracted attention as a potential treatment for a range of medical conditions, including epilepsy and inflammation.

The investigators from the University of Queensland and Botanix Pharmaceuticals Ltd. assessed the antimicrobial activity of synthetically-produced cannabidiol, which does not contain isolation-dependent impurities that could confound biological testing results that are obtained with plant extracts.

Findings from the assessment were presented in a poster at ASM Microbe 2019.

In the investigation, cannabidiol was tested in a “suite of standard antimicrobial assays,” which began with broth microdilution assays against a range of aerobic and anaerobic gram-positive bacteria. The investigators also conducted time-kill, resistance induction, and biofilm disruption experiments with assessment of in vivo activity against methicillin-resistant Staphylococcus aureus (MRSA) in a murine neutropenic thigh infection model.

“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,” the investigators, led by Mark A. Blaskovich, PhD, wrote in the study abstract.

The research team elaborated that notable activity was retained against resistant S aureus strains MRSA, vancomycin-intermediate S aureus (VISA), vancomycin-resistant S aureus (VRSA), Streptococcus pneumoniae (MDR), and Enterococcus faecalis (VRE). Additionally, cannabidiol was found to be bactericidal, and showed low levels of propensity to induce resistance, and was active against MRSA biofilms.

“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,” the investigators wrote.

Based on the findings, the team concluded that the documented anti-inflammatory effects of cannabidiol, combined with extensive safety data and the option for oral delivery, make it a promising new option as an antibiotic.

“The combination of inherent antimicrobial activity and potential to reduce damage caused by the inflammatory response to infections is particularly attractive,” the investigators concluded.

The study, “Cannabidiol Is a Remarkably Active Gram-Positive Antibiotic,” was presented in a poster session on Sunday, June 23, 2019, at ASM Microbe 2019 in San Francisco, California.