UW Chemist Works to Keep Bacteria From Becoming Virulent

Nov 04, 11:05 AM

Current Headlines: By Heather Laroi, The Wisconsin State Journal

Nov. 4--UW-Madison chemist Helen Blackwell is fascinated by conversation, but not the sort that most people are familiar with, the sort with nouns and verbs.

The kind of conversation Blackwell is interested in takes place between bacteria.

Scientists now know that bacteria can, in effect, communicate with each other and function as a group by using the exchange of small molecules as a language of chemical signals.

Blackwell's research focuses on designing ways to hijack these bacterial conversations -- something that could potentially lead to new strategies in fighting some infectious diseases.

"If we can block those chemicals, divert those chemicals or use different ones, we can change these conversations, " Blackwell said. "We can stimulate good behaviors in bacteria and we can turn off bad behaviors. "

In a nod to her innovative avenues of research, Blackwell was recently named to Popular Science magazine 's annual list of the 10 most impressive young scientists in the United States.

At the center of Blackwell 's research is something called "quorum sensing. " The idea is that, through this system of communication, bacteria can sense the overall density of their colony. Once the density reaches a certain threshold, bacteria switch from being isolated cells to a multicellular community, or one that acts as a group.

This switch is significant because it 's only in such groups that bacteria turn virulent.

One form of this group behavior that gets particular attention is biofilms, the goo-like bacterial colonies that show up in nature as the plaque on human teeth or the green slime on rocks. Biofilms also can cause most of the tenacious, and sometimes fatal, hospital infections, such as staphylococcus infections.

"Biofilms are a huge problem in hospital settings because they 'll clog catheters, get in chronic wounds and in burn victims, where you 'll get horrible infections, " said Blackwell, noting that biofilms are largely impervious to antibacterial agents.

"But if you could keep bacteria from growing into that form, if we could control quorum sensing, we could stop all these things, " she said. "That could be a prophylactic antibacterial strategy. You 're not killing them, you 're just keeping them from behaving badly. "

To that end, Blackwell and her team are synthesizing compounds that can turn off quorum sensing systems. Because bacteria also serve positive functions -- like the bacteria in our gut -- the team is also interested in finding compounds that turn on or enhance quorum sensing.

One challenge in working with bacteria, however, is that they are notoriously effective at quickly developing resistance. The hope is that quorum blocking strategies also might provide an avenue to slow that resistance-building process.

That Blackwell 's research selectively focuses on preventing bacteria from doing their jobs as pathogens, not necessarily just killing them, is important, said UW-Madison professor Jo Handelsman, who chairs the bacteriology department and has collaborated with Blackwell.

That could mean drugs that are developed out of the work could remain active longer, she said.

What 's more, Handelsman said, such strategies might also enable existing antibiotics to work better.

"They 're pretty smart, these bugs, " Blackwell said. "The thing is, we have to be smarter than them somehow. "

Blackwell, who joined the UW-Madison faculty in 2002, has earned several significant honors in her career, including a Sloan Fellowship in 2006, the National Science Foundation Early CAREER Award in 2004 and the UW-Madison Chancellors Award for Distinguished Teaching in 2006.

Primary backers of her research are the National Institutes of Health and the National Science Foundation.

At a glance

The discovery: Certain synthetic compounds can interrupt or divert the chemical signals or communication between bacteria.

What it means: Because the ability of bacteria to communicate with each other and function as a group is a critical step in the development of infectious disease, blocking that communication could provide new avenues to fight disease.

Why it's important: Inhibiting bacterial communication could prevent biofilms from forming. Biofilms cause most of the tenacious and sometimes fatal infections in hospitals.

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