Cannabinol (CBN) Shows Strongest Anti-Biofilm Activity Against MRSA Among Five Cannabinoids Tested | Research

The takeaway

Of five major cannabinoids tested against MRSA biofilms, cannabinol (CBN) was the most effective at reducing biofilm biomass and bacterial viability, while CBD caused the most membrane damage but was least effective overall.

Antimicrobial researchers, infectious disease specialists, and pharmaceutical developers exploring novel antibiotics.

All five cannabinoids had MICs of 1-2 ug/mL against MRSA

What the researchers found

All five cannabinoids (CBD, THC, CBN, CBG, CBC) had MICs of 1-2 ug/mL against MRSA. CBN showed the most potent anti-biofilm activity, significantly reducing biofilm biomass and bacterial viability. CBN also induced the highest intracellular ROS levels. CBD was least effective in most anti-biofilm assays but caused the greatest membrane damage, suggesting different mechanisms of action among cannabinoids.

Why it matters

MRSA is a major cause of hospital-acquired pneumonia with few treatment options. This comparative study identifies CBN as the most promising anti-biofilm cannabinoid and reveals that chemically similar cannabinoids work through different mechanisms.

The numbers in context

MICs: 1-2 ug/mL for all five cannabinoids. CBN was most potent for biofilm reduction and ROS induction. CBD caused most membrane damage but was least effective overall.

How the study worked

In vitro study testing five phytocannabinoids against MRSA biofilms using crystal violet staining, resazurin metabolic assay, ROS assay, and propidium iodide membrane integrity test.

What this study cannot tell us

In vitro study only. Biofilm conditions may not replicate in vivo infections. Cannabinoid concentrations achievable at infection sites not established. No combination testing performed.

How to read the evidence

Systematic in vitro comparison with multiple assay methods, but no in vivo or clinical data.

When this study was published

2025 study comparing anti-biofilm activity across major cannabinoids.

The bigger picture

The antibiotic resistance crisis demands novel approaches. Cannabinoids represent an untapped class of antimicrobials, and the finding that different cannabinoids attack bacteria through different mechanisms raises the possibility of synergistic combinations.

Questions still open

Could CBN be combined with conventional antibiotics against MRSA?
Why do structurally similar cannabinoids show different anti-biofilm mechanisms?

Common questions

Can cannabinoids fight antibiotic-resistant bacteria?

All five cannabinoids tested inhibited MRSA at low concentrations. CBN was most effective against biofilms, which are notoriously difficult to treat with conventional antibiotics.

Which cannabinoid is best against MRSA?

CBN showed the strongest overall anti-biofilm activity, though each cannabinoid appeared to work through different mechanisms, suggesting potential for combination approaches.

Read the original research

The anti-biofilm activity of cannabinoids against methicillin-resistant Staphylococcus aureus.

Journal of applied microbiology, 136(9)

View on PubMed ↗Publisher’s paper ↗

Citation

Kwong, Pancy Tsz Hei; Das, Theerthankar; Arnold, Jonathon Carl; Chan, Hak-Kim; Kwok, Philip Chi Lip. (2025). The anti-biofilm activity of cannabinoids against methicillin-resistant Staphylococcus aureus.. Journal of applied microbiology, 136(9). https://doi.org/10.1093/jambio/lxaf214