From cannabis cream to antibiotic dream
A petri dish with the CBD molecular structure drawn with growing bacteria.
A petri dish with the CBD molecular structure drawn with growing bacteria.
Researchers at UQ’s Centre for Superbug Solutions believe they may have found a new class of antibiotics effective against drug-resistant bacteria – all from being asked to help characterise an acne cream!
When contacted by Botanix Pharmaceuticals in 2018 to investigate whether cannabidiol (CBD) – the main non-psychoactive component of cannabis (and the active component of an anti-inflammatory skin cream for acne and atopic dermatitis that Botanix was developing) – also had antibacterial activity, Associate Professor Mark Blaskovich and his team made the surprising discovery that CBD can penetrate and kill a wide range of bacteria.
This included not only the bacteria that cause acne, but also pathogens such as MRSA (golden staph) and those responsible for gonorrhoea, bacterial meningitis and Legionnaires disease.
“This was very good news,” Dr Blaskovich said.
“Gonorrhoea, for example, is Australia’s second most common sexually transmitted disease and can no longer be treated with a single drug because its bacteria are particularly good at developing resistance to antibiotics.
“Some ‘supergonorrhoea’ strains have no reliable antibiotic left to treat them.
“With our discovery that CBD kills a particular sub-set of dangerous pathogenic Gram-negative bacteria – those with an extra outer membrane like the gonorrhoea bacterium – we may have found a new antibiotic that can penetrate this additional layer of defence.”
Bursting the bubble
Dr Blaskovich said cannabidiol was particularly good at breaking down biofilms – the slimy build-up of bacteria, such as dental plaque on the surface of teeth – which help bacteria survive antibiotic treatments.
CBD also does not promote resistance.
One of the studies his team conducted was to expose bacteria over multiple days to sub-lethal concentrations of CBD, trying to force the development of resistance. With other antibiotics, an increasing amount of the compound is required to kill bacteria over time; however, with CBD, this does not happen; it maintains its effectiveness over a long period.
“We think that cannabidiol kills bacteria by bursting their outer cell membranes – a bit like popping bubbles! – but we don’t know exactly how it does that and so we need to conduct further research.”
“However, what we do know is that we can manufacture CBD synthetically and, by slightly changing its molecular structure, we can create chemical analogues (compounds with a molecular structure closely similar to another) that are still active against the bacteria.
“This is particularly exciting because there have been no new molecular classes of antibiotics for Gram-negative infections discovered and approved for human use in decades, and we can now consider designing new CBD analogues that have improved properties – just as penicillin has been modified over the years to make better antibiotics.”
Systemic change
Another study identified an Achilles heel of CBD, though. While it was able to treat topical infections in mice (on the surface of their skin), it did not work on systemic infections (within their body).
“So, what we’re hoping to do is to develop analogues that also have better physico-chemical properties that would allow them to be delivered systemically,” Dr Blaskovich said.
“This means that you’d be able to take a CBD analogue as an oral medication or as an injection to treat infections such as gonorrhoea.”
The team has been collaborating with Botanix Pharmaceuticals, with funding support from the Australian Government's Innovations Connections program, to speed up the research process. They have found that the other ingredients in the ointment or gel used to deliver cannabidiol to the skin make a huge difference in its effectiveness.
“Botanix has progressed a topical CBD formulation into clinical trials for decolonisation of MRSA before surgery, to determine whether CBD would be a suitable alternative for preventing surgical site infection for those patients who are natural carriers of MRSA.
“The first human testing was completed earlier this year and showed promising results. We hope this will pave the way forward for treatments for a range of bacterial diseases.”
Further human trials will be the next step in the process that could see a first-indication CBD-based topical drug approved in two to three years time. Improved versions of CBD will take much longer to reach human use.
“This is why we need to invest in this basic research now, before our existing antibiotics become completely ineffective.”
Their research is published in Communications Biology (DOI:10.1038/s42003-020-01530-y).
For more information, contact:
Associate Professor Mark Blaskovich
Principal Research Fellow, Institute for Molecular Bioscience (Group Leader, Superbugs vs Superdrugs)
+61 7 3346 2994 / 0414 955 380
m.blaskovich@imb.uq.edu.au
Last updated: 7 May 2021
Associate Professor Mark Blaskovich
Associate Professor Mark Blaskovich
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