Alligators often get banged up in battles over territory or food, but Mark Merchant of McNeese State University in Lake Charles, La., noticed they never seem to get infected, despite slimy living conditions in bacteria-filled swamps.

"These alligators tend to get into tussles and fights," says Lancia Darville, a researcher at Louisiana State University in Baton Rouge and a study co-author. "They have torn limbs and scratches that are exposed to all of this bacteria in the water, yet they are never infected."

In a study, presented this week at the American Chemical Society meeting in New Orleans, Merchant and other experts explain why.

When researchers exposed 23 species of bacteria to the serum from alligator blood, all of the bugs were destroyed. Humans typically can defeat only eight of the bacteria.

"That was a good indication that alligators must have some other additional proteins or some proteins that are overly expressed in their system that are either not present in ours or not overexpressed in ours," Darville says.

The study was the first to explore the anti-microbial activity of alligator blood in detail, according to the American Chemical Society. Previous studies by Merchant found that alligators, unlike humans, who need to be exposed to a bug for their immune system to gear up to fight it, are born with what is called an innate immune system.

"They don't need to be exposed to any microorganism such as bacteria, viruses, fungi for their bodies to respond against them," Danville says.

The findings may lead scientists to new drugs that can fight some of the most stubborn infections in humans, such as the "superbugs" that resist antibiotics. If scientists can identify and then mimic the alligator's microscopic defenders, Darville says, they might be able to make stronger bug-fighting pills or creams that could be applied to burns to fight infections.

"Ultimately, we would like to determine what the chemical structure is," Darville says. "Once we can do that, we could eventually develop these into different anti-bacterial and anti-fungal drugs."