WEST LAFAYETTE, Ind. - Whether food-borne bacteria make people sick depends on a variety of factors, and better understanding of the infection process could lead to ways to stop such illnesses from occurring, according to Purdue University scientists.
In the first comprehensive study of the virulence of Listeria monocytogenes, researchers report that how well the bacteria attach to cells does not alone determine the degree of illness. The factors that determine if a person becomes ill and the degree of illness include the levels at which the pathogen attaches to intestinal cells, penetrates cell walls and then moves into other organs, said authors Arun Bhunia and Ziad Jaradat, both of the Department of Food Science. The paper is published in the June issue of Applied and Environmental Microbiology.
Listeria is one of the deadliest food-borne bacteria, with a fatality rate of 20 percent, according to the Centers for Disease Control and Prevention (CDC). It sickens about 2,500 people annually in the United States.
"I'm interested in understanding how the bacteria interacts with the intestinal cells," said Bhunia, who is part of the department's Molecular Food Microbiology Laboratory. "If you eat food that contains these bacteria, the first place they react with cells is in the intestinal track. If we understand the initial interaction of Listeria in the gut, we might be able to prevent the binding and, therefore, the infection."
Listeria enters the body when a person eats contaminated food. Listeria then binds, or adheres, to intestinal cells. If it is a viable, disease-causing strain, it will penetrate the cell wall, causing infection. Once the bacteria have done this, the infected cells will move, or translocate, to another organ, usually the spleen or liver. Very potent Listeria strains also can cause encephalitis, or brain inflammation.