Heart-targeting Listeria increase cardiac disease risk

Jan 26, 2011
Listeria monocytogenes cardiac-invasive strain replicating and moving within infected heart cells. The bacteria (red rods) invade heart cells, multiply, and begin to move through the cell by rearranging cell structural proteins (green) that initially coat the bacteria (green and red rods) and then form long comet tails located directly behind moving bacteria. Credit: Francis Alonzo III

Certain strains of the food pathogen Listeria are uniquely adapted to infect heart tissues and may put people at a higher risk from serious cardiac disease, according to a new study published in the Journal of Medical Microbiology. Developing new diagnostic tests to identify these potentially fatal strains could protect those most at risk, such as those with heart valve replacements.

Researchers from the University of Illinois, Chicago have shown that a sub-population of the monocytogenes display an enhanced ability to infect . They found that mice infected with certain strains of L. monocytogenes had 10-15-fold more bacteria in their heart tissues than mice infected with other strains.

L. monocytogenes is a serious food-borne pathogen which may be found in soft cheeses and chilled ready-to-eat products. Less severe infections lead to gastroenteritis. Serious infections are most commonly associated with the or with the developing fetus in pregnant women. Dr Nancy Freitag who led the study explained how a subset of infections progress differently. "A significant number - about 10% - of L. monocytogenes infections involve the heart. In these cases death rate from cardiac illness is estimated to be up to 35% yet very little is known about how these bacteria infect heart tissues."

The results of the study suggest that these cardiac-associated strains display modified proteins on their surface that enable the bacteria to target the heart, leading to bacterial infection. "We found distinct genetic similarities between the cardioinvasive Listeria versus the other strains that we compared. These similarities all related to the surface proteins on the bacteria," said Dr Freitag.

The group are hoping to develop diagnostic tests based on bacterial . "These tests could be used to distinguish strains of Listeria isolated from food outbreaks, food processing plants, or from clinical infections that place patients at increased risk of ," suggested Dr Freitag. "This would allow health care workers and food safety officials to closely monitor exposed individuals."

The ability to identify cardiac-targeting strains of Listeria could improve infection outcomes and help protect vulnerable groups. "Patients with heart valve replacements or prior cardiac illness are believed to be more susceptible to Listeria cardiac infections. It is not clear exactly why this is so, but it could be that damaged tissue provides an additional entry way for infection," explained Dr Freitag. "We believe that this risk may be increased if the individuals are exposed to cardiac-targeting ," she said.

Explore further: Mycologist promotes agarikon as a possibility to counter growing antibiotic resistance

Provided by Society for General Microbiology

not rated yet
add to favorites email to friend print save as pdf

Related Stories

Scientists advance understanding of food pathogen

Jan 12, 2011

Listeria is an opportunistic pathogen that causes brain infection, blood poisoning, abortion and death for about 500 Americans and a number of farm animals each year. But while its harmful strains can be more lethal than ...

Recommended for you

YEATS protein potential therapeutic target for cancer

Oct 23, 2014

Federal Express and UPS are no match for the human body when it comes to distribution. There exists in cancer biology an impressive packaging and delivery system that influences whether your body will develop cancer or not.

Precise and programmable biological circuits

Oct 23, 2014

A team led by ETH professor Yaakov Benenson has developed several new components for biological circuits. These components are key building blocks for constructing precisely functioning and programmable bio-computers.

User comments : 0