(Note: I initially wrote this piece for a workshop at ComSciCon-PNW 2017)
In January of 2017, the Center for Disease Control and Prevention (CDC) published a much more frightening Morbidity and Mortality Weekly Report than usual: a woman in Nevada had perished from a bacterial infection that no antibiotic in America could fight. Doctors administered 26 different antibiotics to no avail.
“If we’re waiting for some sort of major signal that we need to attack this internationally, we need an aggressive program, both domestically and internationally to attack this problem, here’s one more signal that we need to do that,” Lance Price, the head of the Antibiotic Resistance Action Center at George Washington University, told STAT News.
Recently, researchers at George Mason University made a discovery that could add to science’s arsenal against antibiotic resistance: the presence of powerful antimicrobial chemical compounds in the blood of Komodo dragons.
All classes of life have some natural immune resistance to bacteria that are harmful to them. The first line of defense against bacteria and viruses are compounds called antimicrobial peptides (AMPs), which are typically found in the tissues and organs in the animal that are most exposed to airborne pathogens. Natural and synthetic AMPs have been intensely studied due to their ability to kill or inhibit the growth of antibiotic-resistant bacteria, with the hope that this ability can eventually be used in a clinical application.
Many kinds of AMPs exist, even within the same organism–300 different AMPs live on the surface of a frog’s skin. There is therefore ongoing research to find and categorize different AMPs found in nature, to find the ideal version to fight different kinds of bacteria.
The researchers at George Mason University were particularly drawn to the Komodo dragon because of its incredibly robust immune system. Not only does it recover from physical battles with other members of its species–which often result in open wounds–but it also commonly eats bacteria-ridden dead meat, and bacteria from its bite can contribute to the death of live prey it attacks. In all, the saliva of the Komodo dragon was found to contain 57 separate strains of bacteria, over 90% of which could be classified as disease-causing strains. That this lizard could live with so many pathenogenic bacteria in its mouth and also frequently endure bites from other members of its species justified a deeper look at its collection of AMPs.
The researchers found 48 previously undiscovered AMPs in Komodo dragon blood, and tested 8 of them against 2 antibiotic-resistant strains of bacteria: MRSA and pseudomonas aruginosa. There is only one antibiotic–vancomycin–known to be effective against MRSA, which is responsible for over 10,000 deaths in the U.S every year. Not only that, MRSA has already developed strains that are resistant to vancomycin, which has doctors extremely nervous. In the lab, all 8 Komodo AMPs were able to kill P. aruginosa, and 7 were able to effectively kill MRSA!
However, AMPs do have weaknesses when considering them as a way to fight bacterial infections in a clinical setting: they are sensitive to their environment, and easily break down when confronted with certain enzymes or a high pH; they are costly to synthesize or isolate; it is difficult to engineer them to fight specific strains of bacteria; and several kinds of bacteria are AMP-resistant. Although AMPs have not yet been used to treat human patients, labs across the country are constantly finding more, testing their bacteria-killing potency, and working towards a viable way to use them to treat bacterial infections in humans. The Komodo dragon AMPs join a growing collection being studied by scientists who are racing to find new antimicrobial treatments as bacteria are racing to find ways around them.
Dr. James Johnson, a professor who studies infectious diseases at the University of Minnesota, says many people ask him how scared the public should be about antibiotic resistance. He gave his response to STAT News: “We’re already falling off the cliff,” he said. Hopefully AMP research will eventually help us pull ourselves back up, before it’s too late.
Meredith Fore 