It may sound like snake oil, but a new study suggests scorpion venom contains a substance that can fend off drug-resistant bacteria, including the deadly MRSA.

Drug resistance is increasingly rendering our antibiotic arsenal ineffective against bacteria. According to a CDC study, MRSA caused 36 percent of staphylococcal infections in U.S. hospital intensive-care units in 1992, and as much as 64 percent of infections in 2003. But new research in mice suggests a solution may be hiding right under our feet.

Many peptides (short strings of amino acids) found in many plants and animals have the ability to kill bacteria, fungi, viruses, and parasites. Virologists from China's Wuhan University took a peptide from the venom of a scorpion and modified it to strengthen its antibacterial activity. The modified peptide killed off both *S. aureus *and *E. coli *bacteria, and healed skin infections in mice, the study reported July 5 in the journal PLoS ONE.

The researchers gave mice skin infections and then treated some of them with the scorpion venom peptide. Those infections healed, while untreated infections or those treated with a placebo continued to fester. Under a microscope, skin treated with the venom peptide appeared normal again after four days, whereas the untreated mice suffered deep skin damage.

Image: Cao et al (2012), PLoS ONE

"They showed it’s possible to take this peptide and turn it into an an antimicrobial peptide that can kill a broad range of bacteria that are harmful to humans," said immunologist Michael Zasloff of Georgetown University, who was not involved in the study. "The infections that we create on the backs of mice are not all that different from those that occur on humans."

Studying how bacteria grown outside the body responded to the peptide revealed its mechanism of attack. The peptide bound to substances in the bacteria's cell walls and coated them in tiny spheres, causing the bacteria to burst open and spill their contents (right).

Despite their efficacy, a common problem with antimicrobial peptides is their tendency to split open the infected animal's own blood cells in addition to bacterial cells.

The scorpion venom peptide is quite toxic, microbiologist Robert Hancock of the University of British Columbia, Canada, wrote in an email. But when the researchers tested the modified peptide with human red blood cells, it showed less of a tendency to split human cells than the original peptide had.

If the antibacterial effect works in humans, the new peptide could be a viable treatment for drug-resistant skin infections. Before that happens, it must be shown that the peptide can be produced cost-effectively, is safe to apply to human skin, and is effective in a clinical trial, said Zasloff.

This peptide's clinical implications are merely a side effect of its original purpose: to prevent the scorpion's dinner from spoiling. "As far as a microbe is concerned, once a scorpion’s prey is dead, it’s like a piece of meat," said Zasloff. "It’s what you would want to do if you didn’t have a refrigerator."