"Listeria is everywhere. It's in the food processing plants, it's in animals, it's in the soil, it's in the water," says Martin Wiedmann, Cornell assistant professor of food science and the primary investigator on the project. "And because it can be found in so many places, it provides the ideal model for studying the evolution and ecology of bacterial pathogens."

L. monocytogenes causes death in as many as 20 percent of people who contract listeriosis. It also poses serious health risks to agricultural animals.

While scientists understand the microbiology of the bacterium, how it is transmitted through food, animals, water and soil is not well understood.

"Through broad collaborations with researchers in food science and veterinary medicine, we will systematically develop a biological and evolutionary framework to model and understand the association between distinct groups of Listeria, and the different bacterial hosts and environments," says Wiedmann. "All the while we will be trying to understand the basic biology that forms the base for those associations."

Wiedmann will be joined in the study by Ynte Schukken, Cornell associate professor of veterinary medicine, and Yrjo Grohn, Cornell professor of veterinary medicine, both in the university's College of Veterinary Medicine.

Jonathan Hibbs, bacteriology laboratory director of the New York State Department of Health's Wadsworth Center, Albany, N.Y., will coordinate the collection of fecal samples and perform L. monocytogenes culture analysis.

Michael Wagner, an expert in molecular microbial ecology at the Technical University of Munich, Germany, will develop ways to quantify the ability of different groups of Listeria to survive and multiply inside protozoans, acellular or unicellular microscopic organisms.

Also collaborating on the project are Kathryn Boor, Cornell associate professor of food science; Eugene Madsen, assistant professor of microbiology; and Patrick McDonough, assistant professor of veterinary medicine. Efforts are underway to work with researchers at Zhejiang University and Yangzhou University in China to coordinate data on L. monocytogenes subtypes in China.

Most bacterial species include a genetically diverse group of organisms -- strains -- that often differ in observable characteristics, such as the pathogenic potential for different host species or the ability to compete in various environments.

"Our work will lead to a prediction and identification of human pathogenicity through application of our newly developed evolutionary framework for probing relationships between organism groups and different habitats and environments," says Wiedmann.

For the past nine years, Wiedmann has been collecting samples of Listeria, identifying each strain's unique genetic fingerprint. Every month, the New York State Department of Health sends him new strains, which he identifies and adds to a database.

He also receives Listeria strains from tainted food sent to him by the New York State Department of Agriculture and Markets and from the New York State Veterinary Diagnostic Laboratory. To date, Wiedmann has developed a Listeria database of nearly 900 strains.

In 1999, Wiedmann's database led health investigators to the Listeria strain responsible for a major listeriosis outbreak, which was traced to the Bil Mar Foods/Sara Lee food concern. Ultimately, 35 million pounds of hot dogs and other luncheon meat were recalled. - By Blaine P. Friedlander, Jr.

Related website:

Martin Wiedmann's website

Foodborne Illness Education Information Center

[Contact: Blaine P. Friedlander Jr.]

12-Feb-2001