A new study published in the Journal of Applied Microbiology found that a three-part combination involving silver and two non-intoxicating marijuana compounds may significantly boost antibacterial activity against some of the most concerning healthcare-associated pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli and Pseudomonas aeruginosa. The research was conducted by scientists at the University of British Columbia.
Researchers examined whether several cannabinoids could strengthen silver’s antimicrobial effects in a way that might help address rising antimicrobial resistance while also lowering the amount of silver needed. Silver is already used in healthcare settings because of its broad antimicrobial properties, but its usefulness can be limited by bacterial resistance and toxicity concerns at higher concentrations.
The study found that silver on its own, as well as cannabinoids such as cannabidiol (CBD), cannabichromene (CBC), cannabigerol (CBG), cannabidiolic acid (CBDA), cannabichromenic acid (CBCA) and cannabigerolic acid (CBGA), produced only modest bacteria-slowing effects when used individually. Researchers also found that two-part combinations of silver and cannabinoids did not consistently produce strong or broad effects.
That changed when silver was combined with CBC and CBG. According to the study, those triple combinations were consistently synergistic and bactericidal against MRSA, E. coli and P. aeruginosa. Researchers said the combination lowered silver’s minimum inhibitory concentration by as much as 64-fold in checkerboard testing.
The study also found that the triple combination helped prevent MRSA resistance from emerging during a 20-day serial passaging experiment. In addition, it significantly reduced biofilms formed by MRSA and P. aeruginosa, while also showing reduced cytotoxicity potential in fibroblasts and keratinocytes.
“The increased potency, broad-spectrum bactericidal action and anti-biofilm properties of these novel synergistic silver-CBC-CBG triple combinations may provide a useful solution for bacterial silver resistance and the control of HAI”, concludes the study.
The study’s full abstract can be found below:
Abstract
AimsHealthcare-associated infections (HAI) place substantial burden on healthcare systems globally, with growing antimicrobial resistance (AMR) restricting treatment options, increasing patient mortality and raising the cost of care. Silver is a broad-spectrum antimicrobial used widely to help control HAI. However, its utility is limited by AMR and concentration-dependent cytotoxicity. To address these challenges, we systematically evaluated the antimicrobial amplification properties of non-intoxicating cannabinoids, naturally occurring molecules having a narrow spectrum of antimicrobial activity, aiming to increase the antimicrobial effect of silver against gram-positive and gram-negative HAI pathogens.
Methods and ResultsAdministered individually, silver and cannabinoid compounds CBD, CBC, CBG, CBDA, CBCA and CBGA produced modest bacteriostatic effects on time-kill analysis. Pairwise silver-cannabinoid combinations were neither synergistic nor bactericidal consistently against both Escherichia coli and Pseudomonas aeruginosa. Whereas triple combinations comprising silver (as silver sulfate or nanoparticles), CBC and CBG were consistently synergistic and bactericidal against Staphylococcus aureus (MRSA), E. coli and P. aeruginosa on time-kill analysis, and achieved up to 64-fold lowering of silver MIC on checkerboard assay. Silver-CBC-CBG triple combinations further precluded emergence of MRSA resistance on 20-day serial passaging, ameliorated the potential for cytotoxicity in fibroblasts and keratinocytes, and demonstrated significant clearing of biofilms formed by MRSA (p < 0.001) and P. aeruginosa (p < 0.001).
ConclusionsThe increased potency, broad-spectrum bactericidal action and anti-biofilm properties of these novel synergistic silver-CBC-CBG triple combinations may provide a useful solution for bacterial silver resistance and the control of HAI.
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