Scientists in Australia have found that cannabidiol (CBD), a non-psychoactive ingredient in cannabis, killed all strains of bacteria tested in a lab, including those that are highly resistant to current antibiotics.
Even after being exposed to the drug for 20 days, the bacteria did not become resistant to CBD.
The research team tested a group of bacteria called Gram-positive. This group includes:
- Staphylococcus aureus, which causes the hospital bug MRSA as well as other conditions
- Streptococcus pneumoniae, which leads to pneumonia
- faecalis, which can be life-threatening in those with weak immune systems
Researchers also used CBD in mice to treat a skin infection, and the preliminary study was successful.
Additionally, CBD showed activity against biofilms which can cause difficult-to-treat infections.
Thus far, researchers have only been able to show that CBD works topically. A preliminary study did not find that it works to treat systemic infections. Researchers say that more work must be done to find out how CBD works to kill bacteria without causing resistance. Further research could someday lead to antibiotics being handed out in a local cannabis clinic.
The findings were presented at the American Society for Microbiology, ASM Microbe 2019.
The researchers are quick to caution against ditching antibiotics for CBD. Much of what has been tested has been done in test tubes. A lot more work must be done before CBD can be useful for treating infections in humans.
CBD is not effective against Gram-negative bacteria, which is especially difficult to develop new antibiotics for. This category of bacteria has a selective outer-membrane that stop most drugs from entering the bacterial cell.
This isn’t the first time that researchers found a link between CBD and antibiotic properties. A study from 1976 looked at the antibiotic effects of THC and CBD.
The study was conducted in collaboration with Botanix Pharmaceuticals Ltd., which helped fund the research. The drug-discovery company is investigating the uses of synthetic cannabidiol for treating a range of skin conditions.
The researchers are now planning to conduct another round of trials before moving on to animal studies. The goal is to better understand the types of infections CBD can treat as well as how the compound may be used to kill bacteria.
Botanix also plans to conduct a clinical trial in people to determine whether CBD can remove Staphylococcus aureus bacteria on the skin prior to surgeries to prevent post-surgical infections.
The upcoming studies will be conducted in Australia, where cannabis laws are more lax compared to the U.S. and other countries.