Scientists believe pigs could provide a new weapon to help fight off hospital infections, and maybe superbugs such as MRSA.
Pigs produce the key compound
They have found an anti-bacterial agent produced by the animals can help prevent skin infection in humans.
The molecule - PR39 - is from a family of protective proteins called cathelicidins.
The University of California at San Diego study is published in Proceedings of the National Academy of Sciences.
Tests showed that PR39 in combination with a human cathelicidin can kill streptococcal bacteria.
When scientists delivered PR39 to human skin cells in the laboratory, the cells were better able to fend off infection by the bugs.
Mice engineered to produce PR39 in their bodies also showed increased resistance.
Each year, an estimated 5,000 patients in the UK die as a result of infections picked up in hospital.
The most notorious of these is MRSA, an antibiotic-resistant form of the bug Staphylococcus aureus.
Humans only have one cathelicidin gene, whereas pigs, cows and horses have several.
The new study suggests that having more than one kind of cathelicidin offers extra protection.
The San Diego team synthesised the pig cathelicidin PR39 in the form which only becomes active once inside the body.
They then combined it with the human version, LL-37.
Writing in the journal, the researchers, led by Dr Richard Gallo, said bacteria were becoming increasingly resistant to antibiotics.
This meant that they posed a more profound threat, particularly to the growing number of patients with weakened immune systems.
They said new treatments were needed badly.
Dr Mark Enright, an expert in bacterial infection at Bath University, told the BBC News website the research had potential.
He said: "It would be good to have new, targetted responses to infections.
"Possibly new drugs based on this research could work almost like antibiotics, or be injected into the area of an infection and just have a very local response."