8/11/2019 Quick Study: Research Shows How Listeria Penetrates Small Intestine

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Adapted from image by Mickey Pentecost

The fluorescent green flecks are the Listeria

monocytogenes bacteria as they invade through the

tips of the villi in the intestinal lining, which are

outlined in red. The blue stain illuminates the nuclei

of the villi.

ford Report, February 1, 2006

uick Study: Research shows how Listeriaenetrates small intestine

QUESTION: Listeria monocytogenes  is a

terium that can cause potentially fatal

ctions in the blood (sepsis) or brain

ningitis), or miscarriages in pregnant women.

or contaminated food is the most common

for people to be infected—so! cheeses, deli

ts and raw and smoked fish are the usual

rits. Once someone consumes such food, the

teria that survive the acidity of the stomach

y enter the small intestine, crossing thehelial barrier and then spreading to the liver,

en, central nervous system and, in pregnant

men, the fetus.

ongoing mystery has been how do the Listeria

teria get past the epithelial barrier?

S STUDY  investigated how and where Listeria breaches the tight junctions between the surface

s of the small intestine to invade the body.

researchers used fluorescently labeled probes to document the various interactions between the

teria and the intestinal cells. They found that the microbe can invade cells only at the sites where

epithelium is ejecting dead cells—a constant process in this layer of the intestine.

t happens is this: The living epithelial cells briefly loosen their connection with neighboring cells

hey can cast out dead ones. This transient breach  of the epithelial barrier exposes a protein that

eria latches onto, hitching a ride to the other side . This is the first time that such a mechanism

been visualized.

O MAY BE AFFECTED: According to the Centers for Disease Control and Prevention, about 2,500

es of Listeriosis are reported in the United States annually, with about 500 deaths.

Y IT MATTERS: The ability of Listeria to cause severe, invasive disease depends on its ability to

s the intestinal epithelium. By learning more about how it does this, researchers may devise

er ways to protect against Listeria.

rently, the only preventive measures are thorough cooking and cleaning of food andteurization of dairy products. Antibiotics are the primary treatment for Listeriosis.

EATS: The researchers explored how Listeria gets through the outer layer of the small intestine in

s in culture and in a susceptible animal model, the rabbit, but their work needs to be confirmed in

mans. It also did not address how the bacteria travel from the intestine to cause deeper infection.

NFORD CONNECTION: All of the authors were at Stanford when the work was done. Both senior

hors—associate professor Julie Theriot, PhD, and assistant professor Manuel Amieva, MD, PhD—

n the Department of Microbiology and Immunology. Theriot is also in the Department of 

chemistry. Amieva is also in the Department of Pediatrics.

first author, Mickey Pentecost, is a graduate student in Amieva's lab. Glen Otto, DVM, the fourth

hor, was associate professor of comparative medicine.

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8/11/2019 Quick Study: Research Shows How Listeria Penetrates Small Intestine

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D THIS STUDY: Published in the Jan. 26 online issue of Public Library of Science-Pathogens: 

://pathogens.plosjournals.org. A photograph from the study is featured on the cover of the

nal's January print issue. —Mitzi Baker 

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