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Scientists at the prestigious Pasteur Institute have discovered exactly how the pathogen, Listeria monocytogenes penetrates the body to sicken and sometimes kill vulnerable individuals who eat contaminated foods.

The discovery, reported in the 1 June, 2001 issue of the journal, Science, provides fundamental new information on Listeria. Researchers cautioned that their work doesn't promise an antidote or new treatments for Listeria infection, called listeriosis.

But, the molecule that helps Listeria attack the digestive tract and cross the intestine may ultimately suggest a carrier for delivering various medicines directly to intestinal cells, or to deeper tissues. Thus, the work could prove useful for gene therapy efforts.

"This is a very tricky bacterium," said Pascale Cossart, a professor at the Pasteur Institute in Paris. "For the moment, most people are reasonably safe because the bacterium is sensitive to antibiotics. If it becomes resistant, as we have seen with other bacteria, then it will be critical to know precisely how the infection proceeds in order to design new therapeutic strategies."

A bacterium commonly present in soil, vegetation and sewage, Listeria can contaminate raw vegetables and "ready-to-eat" or processed foods requiring refrigeration, such as soft cheeses, pate and some processed meats.

Listeriosis primarily threatens developing fetuses, newborns, older adults, and those with weakened immune systems, causing meningitis and death among some 30 percent of these patients. In healthy adults, however, symptoms are typically far less serious, ranging from gastrointestinal illness to mild fever and headache.

To cause infection through contaminated food, Listeria must move through the stomach and then cross the intestin
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Contact: Ginger Pinholster
gpinhols@aaas.org
202-326-6421
American Association for the Advancement of Science
31-May-2001