Since Alexander Fleming first purified penicillin in 1928, literally hundreds of millions of lives have been saved from potentially deadly infections. Could you imagine a world without antibiotics? That’s what keeps many doctors up at night, for it is a genuine prospect. Not because antibiotics will vanish overnight but rather because they’ve become increasingly ineffective as microbes have become more resistant.

Bacteria that are ‘resistant’ can multiply in the presence of various therapeutic levels of an antibiotic. In time such strains can become so widespread that new classes of antibiotics need to be used. But what happens if nothing at your disposal works?

The war against antibiotic-resistant bacteria has often been likened to an arms race, and scientists may have found an unlikely novel weapon: a cannabis compound.

According to new research published by scientists at the University of Queensland in Australia, synthetic cannabidiol, also known as CBD, can kill the bacteria responsible for gonorrhea, meningitis, and legionnaires disease.

“This is the first time CBD has been shown to kill some types of Gram-negative bacteria. These bacteria have an extra outer membrane, an additional line of defense that makes it harder for antibiotics to penetrate,” Dr. Mark Blaskovich, Director of the Centre of Superbug Solutions at the University of Queensland, said in a statement.

Gonorrhea is one of the most common sexually transmitted infections, but thanks to antibiotics it has always been easy to get rid of — until recently. Millions of people were prescribed antibiotics to cure their gonorrhea infection, but not everyone used the drugs as instructed. Some didn’t go through the full course of antibiotics, training a new generation of drug-resistant bacteria.

Already, older treatments such as penicillin are ineffective. In developed countries, for some cases doctors have reported that no available treatment options are effective. According to the World Health Organization, there are only three potential drug treatments in various stages of trials, but it’s not clear if they will prove effective against novel strains of gonorrhea that are becoming more widespread across the world.

This is where synthetic CBD may lend a helping hand. The second most abundant cannabidiol found in the plant Cannabis sativa has become increasingly popular in recent years. Unlike THC, CBD is non-psychoactive, meaning it doesn’t make you ‘high’. People who have used it, however, claim that it is relaxing and can ease anxiety.

Now, Blaskovich and colleagues have shown it may also act as an antibiotic in some situations. Besides gonorrhea, synthetic CBD was widely effective against a much larger number of Gram-positive bacteria than previously known, including antibiotic-resistant pathogens such as MRSA (methicillin-resistant Staphylococcus aureus) or ‘golden staph’.

CBD was particularly effective at breaking down biofilms, such as dental plaque on the surface of teeth.

The scientists still aren’t exactly sure how CBD destroys bacteria. For now, they just know it works well. What’s more, it also seems less likely to contribute to bacterial resistance.

“Cannabidiol showed a low tendency to cause resistance in bacteria even when we sped up potential development by increasing concentrations of the antibiotic during ‘treatment’,” the researchers in Australia said.

“We think that cannabidiol kills bacteria by bursting their outer cell membranes, but we don’t know yet exactly how it does that, and need to do further research.”

The research is exciting considering we haven’t seen a new class of antibiotics for gram-negative infections since the 1960s. In the future, Botanix Pharmaceuticals Limited, a company that contributed formulation expertise to the research, is planning to test a topical CBD formulation in clinical trials for decolonization of MRSA before surgery. Phase 2 clinical trials are expected to commence early this year.

The findings appeared in the journal Communications Biology.