Study Finds Pneumonia Bacterium Leaves Tiny Lesions in the Heart

For the first time, a team of researchers has linked pneumonia with heart failure.

Led by School of Medicine at The University of Texas Health Science Center, San Antonio, the researchers found that the bacterium Streptococcus pneumoniae - known to be the leading cause of pneumonia - causes physical damage to the heart. They noticed that the bacterium leaves tiny lesions and this was detected in mouse, rhesus macaque and even in the human autopsy tissue samples.

They noticed that the bacterium Streotococcus pneumonia in blood attacked the heart and formed lesions in the myocardium i.e. the muscular middle layer of the heart wall. The team also successfully recognized the underlying mechanism by which the bacterium spreads across endothelial cells in the cardiac blood vessels.

"If you have had severe pneumonia, this finding suggests your heart might be permanently scarred," said study senior author Carlos Orihuela, Ph.D., associate professor of microbiology and immunology at the UT Health Science Center San Antonio.

What remains a mystery is whether the small lesions cause the increased risk of death in humans or is it the scarring that occurs later is permanent, lowering the human cardiac function in those who have recovered from the severe infectious disease. The team further plans to study the long term ramification in non-human primates.

"Fortunately, we have a candidate vaccine that can protect against this," Dr. Orihuela said. This candidate vaccine promises to curb the spread of the infection into the heart as well the toxin that damages the heart muscle cells called cardiomyocytes. In the animal study, the researchers noticed that the vaccine offered protection to the immunized animals against the formation of cardiac lesions.

The finding is documented in the journal PLOS One.