Pneumonia bacterium may permanently scar the heart

The bacterium that causes pneumonia leaves tiny lesions in the heart, physically damaging the organ, according to a new study.
Researchers at The University of Texas Health Science Center at San Antonio said the long-observed association between pneumonia and heart failure now has more physical evidence.
The researchers found proof that Streptococcus pneumoniae, the leading cause of community-acquired pneumonia, actually physically damages the heart.
The bacterium leaves tiny lesions that researchers detected in mouse, rhesus macaque and human autopsy tissue samples.
"If you have had severe pneumonia, this finding suggests your heart might be permanently scarred," said study senior author Carlos Orihuela, associate professor of microbiology and immunology at the UT Health Science Center San Antonio.

It's not yet known whether the small lesions contribute to increased risk of death in humans or if the scarring that occurs afterward is permanent, ultimately diminishing cardiac function in individuals who have recovered from a severe infectious disease episode.

Streptococcus pneumoniae in the blood invaded the heart and formed lesions in the myocardium, the muscular middle layer of the heart wall, the researchers showed.
The team identified mechanisms by which the bacterium is able to spread across endothelial cells in cardiac blood vessels to travel to and infect the heart.
"Fortunately, we have a candidate vaccine that can protect against this," Orihuela said.

The candidate vaccine acts to stop both the movement of the infection into the heart and the toxin that kills heart muscle cells called cardiomyocytes. The vaccine protected immunised animals against cardiac lesion formation, the study showed.
The study was published in the journal PLoS Pathogen.