The bacteria, Listeria monocytogenes, can cause severe illness or death in people with weakened immune systems and may cause miscarriage in pregnant women. "Twenty to 40 percent of people with listeriosis" - the disease caused by Listeria infection - "die even after antibiotic treatment," said Jonathan Hardy, PhD, the study's first author and a research associate in the Department of Pediatrics. The research is published in the Feb. 6 issue of Science.
Listeriosis causes about 500 U.S. deaths annually; pregnant women are about 20 times more likely than other healthy adults to become infected. Unlike many bacteria, Listeria is perfectly happy growing at refrigerator-like temperatures and can survive for long periods outside of its many animal hosts. It is most commonly found in foods such as soft cheeses and deli meats - products pregnant women are often told to avoid.
"To have discovered a chronic carrier state in the gall bladder of an animal model, suggesting a potential source of food contamination, is important," said senior author Christopher Contag, PhD, assistant professor of pediatrics and of microbiology and immunology. Until now, it had been thought that tainted food came primarily from infected animals or from soil or water harboring the hardy bacteria.
Hardy and colleagues at Stanford and Xenogen Corp. used a unique imaging technique to track the ebb and flow of Listeria infection in live mice. They tagged the bacteria with a luminescent molecule that can be non-invasively detected in living tissue, and then analyzed when and where the lunch-meat lurkers popped up. The ab
Contact: Krista Conger
Stanford University Medical Center