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Machines Like Us

Discovery opens door to attacking biofilms that cause chronic infections

Sunday, 15 July 2012
by Robert Sanders

Veysel Berk image

A clever new imaging technique discovered at the University of California, Berkeley, reveals a possible plan of attack for many bacterial diseases, such as cholera, lung infections in cystic fibrosis patients and even chronic sinusitis, that form biofilms that make them resistant to antibiotics.

By devising a new fluorescent labeling strategy and employing super-resolution light microscopy, the researchers were able to examine the structure of sticky plaques called bacterial biofilms that make these infections so tenacious. They also identified genetic targets for potential drugs that could break up the bacterial community and expose the bugs to the killing power of antibiotics.

“Eventually, we want to make these bugs homeless,” said lead researcher Veysel Berk, a postdoctoral fellow in the Department of Physics and the California Institute for Quantitative Biosciences (QB3) at UC Berkeley.

Berk and his co-authors, including Nobel laureate and former UC Berkeley professor Steven Chu, report their findings in the July 13 issue of the journal Science.

“In their natural habitat, 99.9 percent of all bacteria live as a community and attach to surfaces as biofilms; according to the National Institutes of Health, 80 percent of all infections in humans are related to biofilms,” Berk said.

The researchers were able to employ new techniques that allowed them to zoom into a street-level view of these biofilms, where they learned “how they grow from a single cell and come together to form rooms and whole buildings,” Berk said. “Now, we can come up with a logical approach to discovering how to take down their building, or prevent them from forming the building itself.”

Combining super-resolution microscopy with the technique Berk developed, which allows continuous labeling of growing and dividing cells in culture, biologists in many fields will be able to record stop-motion video of “how bacteria build their castles,” he said.

“This work has led to new insights into the development of these complex structures and will no doubt pave the way to new approaches to fighting infectious disease and also bacteriological applications in environmental and industrial settings,” said Chu, a former UC Berkeley professor of physics and of molecular and cell biology and former director of the Lawrence Berkeley National Laboratory.

Bacteria are not loners

The popular view of bacteria is that they are free-living organisms easily kept in check by antibiotics, Berk said. But scientists now realize that bacteria spend most of their lives in colonies or biofilms, even in the human body. While single bacteria may be susceptible to antibiotics, the films can be 1,000 times more resistant and most can only be removed surgically.

Implants, such as pacemakers, stents and artificial joints, occasionally become infected by bacteria that form biofilms. These biofilm sites periodically shed bacteria – adventurers, Berk calls them – which can ignite acute infections and fever. While antibiotics can knock out these free-swimming bacteria and temporally calm down the infection, the biofilm remains untouched. The only permanent solution is removal of the biofilm-coated device and replacement with a new sterilized implant.

A permanent bacterial biofilm in the sinuses can ignite an immune response leading to chronic sinus infections, with symptoms including fever and cold-like symptoms. So far, the most effective treatment is to surgically remove the affected tissue.