Sights Set on Bacteria

Death from a minor cut or sore throat doesn’t figure highly among modern anxieties, but times may be changing: According to the World Health Organization, antibiotic-resistant bacteria are flourishing worldwide amid overuse of the former wonder drugs.

Yet there might be a way to fight bacteria without antibiotics by literally exploding the pests with a high-tech version of a process that evolved in nature.

Daniel Nelson, an associate professor in the Department of Veterinary Medicine and at the Institute for Bioscience and Biotechnology Research in Rockville, extracts enzymes called lysins from viruses that infect bacteria—bacteriophages—and engineers bacteria-fighting drugs he’s dubbed “enzybiotics.”

Lysins work by breaking chemical ties in bacterial cell walls, “like cutting the steel girders in a building,” he says.

Previous lysins from his lab have killed animal and human pathogens like staph and pneumonia, but a new one he’s identified destroys one of the scariest superbugs—MRSA, which haunts hospitals and kills thousands of Americans yearly. Unlike older enzymes, the MRSA-killer cleaves the cell wall in two dimensions, like cutting both vertical and horizontal girders in a building.

“That means it has to chew up even less of the cell wall to have this explosion,” he says.

Enzybiotics are only now entering human testing, and they may eventually be used in combination with antibiotics.

“In the lab, we can dump enough antibiotic on something to kill it, but at a level that’s toxic,” he says. “By using enzybiotics to break up the cell wall, you could use a far lower antibiotic dose and have it be effective.”

One advantage of enzybiotics over antibiotics is that they can target specific harmful bacteria, says Kevin McIver, a professor of cell biology and molecular genetics. He studies Streptoccus pyogenes—the pathogen behind strep throat and “flesh-eating disease,” and uses lysins from Nelson’s lab in his research.

“Since lysins can be very specific to a single species, it prevents the killing of our ‘good’ microbiota in our bodies or in animals,” he says. “Dr. Nelson’s lab is modifying these natural lysins to enhance their capabilities further, making them even more effective antimicrobial agents.”

And perhaps best of all, Nelson says that researchers have been searching for enzybiotic resistance in bacteria—and have yet to find it.