Researchers took blood from American alligators
Proteins isolated from alligator blood may lead to new antibiotics to treat "superbugs", such as MRSA.
Speaking at the American Chemical Society conference, US researchers said the discovery could also lead to treatments for severe burns and ulcers.
Alligators can suffer serious injuries during fierce territorial battles but heal quickly despite contact with bacteria, viruses and fungi.
Antibiotic resistance is on the rise yet there is a lack of new treatments.
Humans build up immunity to infection-causing organisms after coming into contact with them.
But, the Louisiana researchers said, previous work has shown alligators have a particularly strong immune system which can fight microorganisms such as fungi, viruses, and bacteria without being previously exposed to them.
The team collected blood samples from American alligators after injecting them with a substance to stimulate their immune systems.
They then isolated infection-fighting white blood cells and extracted antibiotic proteins.
In laboratory tests, tiny amounts of the protein extracts killed a wide range of bacteria, including MRSA.
The proteins also killed six out of eight different strains of Candida albicans - a yeast infection which can be a serious problem in people with weakened immune systems, such as Aids patients.
It is hoped the proteins can be used as a basis for new antibacterial and antiviral drugs to treat human infections.
The next step is to work out the exact chemical structure of the antibiotic proteins.
The researchers are also looking into the possibility of using the alligator proteins in developing treatments for HIV after showing white blood cells from alligators could destroy the virus in a Petri dish.
Biochemist Dr Mark Merchant, who has been looking into the antibiotic properties of alligator blood for the past four years, said the team was very excited about the potential for developing antibacterial and antifungal treatments.
"There's a real possibility that you could be treated with an alligator blood product one day."
He predicts creams made from alligator blood could be used for treatment of diabetic foot ulcers or to keep infections at bay in burn patients.
Dr Merchant has done similar work using Australian crocodiles.
Professor Paul Williams, an expert in microbiology at the University of Nottingham said most antibiotics in use today were developed a long time ago.
"We're basically running out so we need to develop new antibiotics.
"People are looking for peptides in frog skin and alligators, for example, to see if they are effective at reducing virulence, killing bacteria or improving the ability of the immune system to fight infection.
"But lots of them have never made it into the clinic."