Pneumonia Bacterium Leaves behind Tiny Lesions in Heart, study


Texas University researchers have discovered a relation between pneumonia and heart failure.

The researchers said that bacterium Streptococcus pneumoniae, the leading cause of community-acquired pneumonia, physically damages the heart by leaving tiny lesions.

"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, in a press release.

For the study, the researchers conducted experiments mouse, rhesus macaque and human autopsy tissue samples.

The researchers found that streptococcus pneumoniae in the blood attacked the heart and formed lesions in the myocardium, the muscular middle layer of the heart wall. The team identified mechanisms through which the bacterium spread across endothelial cells in cardiac blood vessels to travel to and contaminate the heart.

In the study, the researchers have not yet determine whether these small lesions causes increased death risk in humans or if the scarring that occurs afterward is permanent - ultimately disrupting cardiac function in patients recovered from a severe infectious disease episode.

"Fortunately, we have a candidate vaccine that can protect against this," Orihuela said.

The candidate vaccine stopped both the growth of the infection into the heart and the toxin that kills heart muscle cells called cardiomyocytes. In the study, the vaccine protected immunized animals from cardiac lesion formation.

The finding is published in the journal PLOS Pathogen.

According to a 2013 Stanford University study, staphylococcus aureus, the bacteria known to cause food poisoning, sepsis and pneumonia, have now been found to hide in deeper parts of the nose than previously believed.

"About one-third of all people are persistent S. aureus carriers, another third are occasional carriers and a remaining third don't seem to carry S. aureus at all," Dr. David Relman, a professor of medicine, microbiology and immunology, said in a statement. "Not everyone who carries S. aureus gets sick. When they're out walking the streets and otherwise healthy, attempts to rid them of their S. aureus are not necessary, and even sometimes futile."

"But once a carrier enters a hospital with an underlying illness or a weakened immune system or a high likelihood of undergoing skin-penetrating procedures, S. aureus carriage is a major liability."

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