Sept. 4, 2008 -- Chemicals in marijuana may be useful in fighting MRSA, a kind of staph bacterium that is resistant to certain antibiotics.

Researchers in Italy and the U.K. tested five major marijuana chemicals called cannabinoids on different strains of MRSA (methicillin-resistant Staphylococcus aureus). All five showed germ-killing activity against the MRSA strains in lab tests. Some synthetic cannabinoids also showed germ-killing capability. The scientists note the cannabinoids kill bacteria in a different way than traditional antibiotics, meaning they might be able to bypass bacterial resistance.

At least two of the cannabinoids don't have mood-altering effects, so there could be a way to use these substances without creating the high of marijuana.

MRSA, like other staph infections, can be spread through casual physical contact or through contaminated objects. It is commonly spread from the hands of someone who has it. This could be in a health care setting, though there have also been high-profile cases of community-acquired MRSA.

It is becoming more common for healthy people to get MRSA, which is often spread between people who have close contact with one another, such as members of a sports team. Symptoms often include skin infections, such as boils. MRSA can become serious, particularly for people who are weak or ill.

In the study, published in the Journal of Natural Products, researchers call for further study of the antibacterial uses of marijuana. There are "currently considerable challenges with the treatment of infections caused by strains of clinically relevant bacteria that show multi-drug resistance," the researchers write. New antibacterials are urgently needed, but only one new class of antibacterial has been introduced in the last 30 years. "Plants are still a substantially untapped source of antimicrobial agents," the researchers conclude.