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Running out of antibiotics, scientists turn to enzymes to kill superbugs

In a new study, researchers suggest that lytic enzymes, not antibiotics, may be tool to kill otherwise resistant superbugs like MSRA.
Written by Andrew Nusca, Contributor

By now, it's general knowledge that the heavy, widespread use of antibiotics in modern society has provoked bacteria to get smarter and evolve, rendering the very drugs used to kill them ineffective.

The concern: that an antibiotic-resistant superbug like MRSA could decimate our pharmaceutical defenses before we've crafted a better, more powerful answer to it.

With backs against the wall, scientists are returning to proteins for the answer.

Lytic enzymes attack bacteria by piercing their cell walls. Naturally present in everything from viruses and bacteria to our own body fluids -- tears, saliva, mucus --  they were once the preferred mode of keeping bacteria at bay,

But if lytic enzymes are the equivalent of a sharp knife, killing a limited range of bacteria with stunning efficiency, antibiotics -- discovered five years later, in 1928 -- are a nuclear bomb, destroying all comers.

Since that moment, research on the proteins' abilities slowed to a trickle. But as Mother Nature outpaces scientific progress and the effectiveness of antibiotics fades, scientists believe lytic enzymes could again be used -- this time to kill certain superbugs, while leaving beneficial bacteria intact.

Research published this week in the journal Physical Biology shows a group of U.S. researchers taking the first step toward that goal.

Two Georgia Institute of Technology quantitative biologists, Joshua Weitz and Gabriel Mitchell, partnered with University of Maryland biochemist Daniel Nelson to develop a method to evaluate lytic enzymes for optimum bacteria-killing characteristics.

Specifically, that means looking on a microscopic scale to determine the rate at which the enzymes pierce cell walls, a fatal move that throws a bacterium's internal pressure out of equilibrium.

The scientists in their own words:

While lytic enzymes and their associated antimicrobial activity have been studied for decades, their use as therapeutics has only recently been investigated in detail. We measured the amount of light passing through a bacterial solution, in much the same way as astrophysicists use light measurements for far-away galaxies: to infer processes at a far different scale based on interpreting the information contained in the light coming from them.

By mapping out the death-inducing cellular processes caused by the enzymes, the researchers were able to quantify the proteins' effectiveness, as well as estimate what bacteria may be most susceptible to them.

"We believe we have taken the first step down a road which will allow us to identify more enzymes, choose those with the best activity, and engineer even higher activity, to develop an effective therapy against a wide range of dangerous superbugs," the researchers said.

This post was originally published on Smartplanet.com

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