Seely on Science: Chemical agents wage war against bacteria

2012-08-24T06:00:00Z Seely on Science: Chemical agents wage war against bacteriaRON SEELY | Wisconsin State Journal | | 608-252-6131

Remember chemistry sets?

All those test tubes and neat little packets of different chemicals. A microscope. Maybe even a small Bunsen burner. And the promise of making something boil or foam or maybe even modestly blow up.

Chances are, if you probe a bit into the background of many scientists, there is a chemistry set in their past. Scratch the surface of just about any branch of science and you'll find chemistry. Yet it remains in some ways the invisible science as its practitioners toil away — too often unnoticed and underappreciated — figuring out the chemical underpinnings of the natural world and chemical solutions to some of our thorniest problems.

On the UW-Madison campus, for example, chemistry is showing us a way to better understand and fight one of the most dangerous of the many bacteria that have become resistant to antibiotics. The bacterium is called Acinetobacter baumanni, or A. baumanni, and it proved a terror in front-line hospitals in Iraq, earning the nickname "Iraquibacter."

But in her laboratory at UW-Madison, chemist Helen Blackwell and her colleagues have spent a decade unlocking some of the chemical secrets of A. baumanni and may be on the verge of finding a new weapon against the stubborn pathogen.

Chemistry, it turns out, underlies that bacterium's ability to become deadly.

The bacterium relies on a behavior called "quorum sensing" to do its dirty work. Using chemical signals, the bacteria gather and form into "biofilms." Once they reach a critical mass — Blackwell calls it "swarming" — they work together to wreak havoc by coating everything from catheters to breathing tubes. Thousands of patients die annually from infections caused by the microbe, contracting pneumonia and urinary tract and blood infections.

"It's like they're saying 'Hey, if there are enough of us around, let's change how we behave,'" Blackwell said.

This kind of communication long has fascinated Blackwell. In fact, she said she spent years studying chemical signaling in plants. Because they can't move, she said, plants have developed remarkable signaling systems to send and receive information from the world around them.

Now, Blackwell has drawn on her understanding of signaling to disrupt the process in A. baumanni. Stored in a cooler in her lab are vials and vials of synthetic compounds which she has created over the years. "That's one of the neat things about chemistry," Blackwell said. "You can make things that nature doesn't make."

By continually tweaking the makeup of the compounds, Blackwell has created combinations of chemicals that can be used to interrupt A. baumanni's chemical signaling, thereby effectively blocking its ability to congregate into biofilms.

The work holds out the promise of an eventual medical treatment that would short-circuit the workings of bacteria that can be so deadly for recovering patients. And this particular approach to thwarting bacteria has an important advantage, Blackwell said. Traditional anti-bacterial agents destroy the bacteria in one way or another and push into overdrive the evolutionary machinery that prompts a bacterium to rapidly reproduce and eventually develop ways to resist the agents that are trying to destroy it.

Blackwell's approach, however, has the advantage that it doesn't kill the bacteria, it just disrupts its behavior. As a result of this somewhat sneakier approach, the bacterium isn't pushed as rapidly to change and the development of resistance can be significantly slowed, Blackwell said.

Even with the promise of the research, Blackwell cautioned there is much left to study and the compounds she has created will be most promising in the short term as tools for better understanding the phenomenon of quorum sensing.

But that is how science proceeds. Unlike TV shows and movies, science in the real world takes decades. In real labs, scientists have few eureka moments. Instead, they spend years trudging over and over again between a cooler and a lab bench carrying small vials of chemicals that are placed in a dish to react with other chemicals. They wait for a reaction, take notes and then do it over again. And again. And again. And again.

That, Blackwell said, is fundamental research.

And, yes, Blackwell had a chemistry set.

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