Boston, MA--For the first time, scientists have found that bacteria can use a Sonar-like system to spot other cells (either normal body cells or other bacteria) and target them for destruction. Reported in the December 24 issue of Science, this finding explains how some bacteria know when to produce a toxin that makes infection more severe. It may lead to the design of new toxin inhibitors. "Blocking or interfering with a bacterium's "detection" mechanism, should prevent toxin production and limit the severity of infection," says Michael Gilmore, PhD, lead author of the study, and currently director of research at the Schepens Eye Research Institute and professor of ophthalmology at Harvard Medical School.

Gilmore and his team have spent years studying the bacterium known as Enterococcus faecalis, one of the leading causes of hospital-acquired infections, to find new ways to treat them. These infections are frequently resistant to many, and sometimes all, antibiotics. Tens of thousands of deaths due to antibiotic resistant infection occur each year in the US, adding an estimated $ 4 Billion to health care costs. Scientist have known since 1934 that especially harmful strains of Enterococcus produce a toxin that destroys other cells, including human cells and even other types of bacteria. They also knew that this toxin was made only under some conditions. Until Gilmore's study, scientists were unable to explain how the Enterococcus knew when to make it.

In the Science study, Gilmore and his team found that this toxin is made whenever there is another cell type in the environment near the bacterium, such as a human blood cell. They discovered how these bacteria know when other cells are present, and respond accordingly.

In the laboratory, the team found that Enterococcus releases two substances into the environment. One substance sticks to foreign cells. The second substance reports back and tells the Enterococcus to make the toxin. If no cell
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Contact: Patti Jacobs
pjacobs12@comcast.net
617-872-0364
Schepens Eye Research Institute
23-Dec-2004

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