Severe pneumonia may permanently damage your heart as pneumonia bacterium leaves tiny lesions in the heart, a study suggests.

The researchers found proof that Streptococcus pneumoniae, the leading cause of community-acquired pneumonia, actually physically damages the heart.

The researchers detected tiny lesions that the bacterium leaves 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 University of Texas Health Science Center at San Antonio, US.

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 noted.

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 immunized animals against cardiac lesion formation, the study showed.

The study appeared in the journal PLoS Pathogen.