CHICAGO, Jan. 27 (UPI) -- U.S. researchers report they have isolated a strain of food-borne bacteria from the heart of a patient with endocarditis.
Researchers at the University of Illinois at Chicago College of Medicine found 90 percent of mice with the "cardiac strain" of the food-borne bacteria listeria monocytogenes developed endocarditis -- an inflammation of the inner layer of the heart, the endocardium.
Mice with the cardiac strain had 10 times as much bacteria in the heart than mice infected with other strains of the bacteria.
The study, published online in the Journal of Medical Microbiology, indicated a search for more strains of the bacteria yielded 10 and, of these, one caused endocarditis.
"Usually with endocarditis there is bacterial growth on heart valves, but in this case the infection had invaded the cardiac muscle," chief investigator Nancy Freitag said in a statement.
Freitag suggested cardiac-associated strains have surface proteins that may enable the bacteria to more easily enter heart cells.
Freitag noted the bacteria, which can grow in refrigerated foods, is quite common but infections are usually mild.
"As foods are being produced with a longer and longer shelf life, listeria infection may become more common," Freitag said. "In combination with an aging population that is more susceptible to serious infection, it's important that we learn all we can about these deadly infections."