Listeria May Cause Fatal Heart Infection

Researchers at the University of Illinois at Chicago College of Medicine just discovered that some strains of food borne bacteria can invade the heart, which can result in significant and “difficult-to-treat heart infections”, said Science Daily. The study appears, online, in the Journal of Medical Microbiology.

Listeria monocytogenes, the bacteria that leads to the food borne illness Listeriosis, is generally found in soft cheeses and refrigerated ready-to-eat foods, said Science Daily. For susceptible populations and the elderly, food poisoning infection with the Listeria pathogen can cause significant illness linked to issues with the central nervous system as well as the developing fetus and placenta, said Science Daily.

As we have long reported, consumption of food contaminated with Listeria monocytogenes can cause Listeriosis, a potentially fatal food borne illness. While healthy people rarely contract Listeriosis, the symptoms of Listeria poisoning can cause high fever, severe headache, neck stiffness, nausea, abdominal pain, and diarrhea.

The study’s principal investigator, Nancy Freitag, associate professor of microbiology and immunology, said that some 10 percent of serious infections with the food borne illness Listeriosis involve a cardiac infection that is difficult to treat, with over one-third leading to death, wrote Science Daily.

For the study, the team isolated a Listeria strain taken from a patient diagnosed with endocarditis, infection of the heart, said Science Daily. Typically, endocarditis is accompanied with bacterial growth on the heart valves; however, this case involved the infection invading the heart muscle. “This looked to be an unusual strain, and the infection itself was unusual,” Freitag said, quoted Science Daily.

We have often explained that Listeria monocytogenes, which reportedly infects about 2,500 people in the U.S., killing 500, is known to result in serious, sometimes fatal, infections in those with weakened immune systems, such as infants, the elderly, persons with HIV infection, and those undergoing chemotherapy. In pregnant women, Listeria food poisoning can result in miscarriage, stillbirth, or birth of a baby suffering from the infection. Pregnant women are about 20 times likelier than others to be infected; Listeriosis can kill fetuses, prompt premature births, and can lead to hearing loss or brain damage in newborns and, notable to this study, can prompt neurological effects and cardio respiratory failure in adults. As Science Daily noted these infections have not been broadly studied and are not fully understood.

In lab tests, the team found that when injecting mice with either the cardiac isolate or a lab strain, those mice infected with the cardiac isolate tested with 10 times more cardiac bacteria and 90 percent tested with heart infections, versus the mice infected with the lab isolate, said Science Daily. In testing with a total of 10 Listeria strains, only one other targeted the heart, noted Science Daily.

“They infected the heart of more animals and were always infecting heart muscle and always in greater number,” Freitag said of the cardiac isolate of the Listeria pathogen. “Some strains seem to have this enhanced ability to target the heart for infection. These strains seem to have a better ability to invade cardiac cells,” she said, quoted Science Daily. “Listeria is actually pretty common in foods. And because it can grow at refrigerated temperatures, as foods are being produced with a longer and longer shelf life, Listeria infection may become more common. 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,” added Freitag, reported Science Daily.