How Bacterial Pneumonia Damages the Heart

STREPTOCOCCUS-PNEUMONIAEBacterial pneumonia is an infection that affects one or both of the lungs. It creates an inflammation of the alveoli (the lung's air sacks) and causes them to fill up with cellular debris, pus, and fluid. This makes it more difficult for the body to turn oxygen into carbon dioxide. The most common symptoms of bacterial pneumonia are pain while breathing and breathlessness. Bacterial pneumonia can be mild or very serious. A severe case of bacterial pneumonia can even cause respiratory failure and death. Unfortunately, those are not the only risks and dangers that bacterial pneumonia creates. Recent studies have shown that bacterial pneumonia can do serious damage to the heart.

Several studies have been done to determine whether bacterial pneumonia has an impact on the heart. Scientists analyzed the autopsies of humans, mice, and rhesus macaques and found that living things that have suffered from pneumonia have a much higher possibility of acquiring heart problems in the future. The mice autopsies showed more troponin in the blood sample of mice sick with bacterial pneumonia than in the blood of healthy mice. Troponin is a well-known signal of a heart problem. These mice were also found to have an abnormal heart rate.

Bacterial Pneumonia causes lesions in the heart

By analyzing the tissue of animals and humans sick with pneumonia, researchers were able to conclude that the bacteria that is responsible for pneumonia spreads across the endothelial cells in the cardiac arteries and infects the heart. The bacteria can cause tiny lesions within the myocardium of the heart. The myocardium is the muscular middle layer of the wall of the heart. The micro lesions leave the heart scarred and later lead to necrosis of myocardiocytes. The heart cells are killed off by a poisonous substance, pneumolysin, which is produced by the bacteria. It is still not clear whether these lesions increase the chance of death directly, or if they hurt cardiac function, thus creating heart problems.

Pneumonia puts stress on the heart and can lead to blood clot formation


Pneumonia also makes it more difficult for the lungs to transfer oxygen from the air into the blood while at the same time, causing the heart to demand more oxygen. This puts a lot of stress on the body and can lead to heart problems. Medical researchers have found another reason for the connection between bacterial pneumonia and heart problems. Pneumonia increases the amount of cytokine, a chemical signal, in the blood. This cytokine is known to cause the formation of blood clots. These blood clots decrease the effectiveness of the heart and put it at risk.

The dangers of antibiotic drugs used as treatment

Interestingly enough, the antibiotics that were developed to deal with bacterial pneumonia also have a damaging effect on the heart. Most of these antibiotics used for treating pneumonia, only cause the bacteria to burst open and expel its poisonous contents outward. The pneumolysin is released directly into the heart causing severe damage. There is hope that other medications will be able to treat pneumonia without putting the heart at extra risk. Antibiotics known as the bacteriostats may be the more appropriate form of medication.


Bacterial Pneumonia and heart problems often go hand in hand. In fact, as many as 20% of people who are hospitalized for bacterial pneumonia are also found to have potentially dangerous heart problems. These heart problems can evolve into heart attacks, heart failure, and abnormal heart rhythms. That is not surprising as pneumonia affects the heart in many ways. It creates micro-lesions on its surface, causes the death of heart cells and heart muscle cells, increases clot-formation,  and puts a lot of pressure on the heart. By knowing that the two are often connected, it is possible to diagnose heart problems early on and treat them in time.




1.  Carlos Orihuela, Ph.D., associate professor, department of microbiology and immunology, University of Texas Health Science Center, San Antonio; Gregg Fonarow, M.D., professor, cardiology, University of California, Los Angeles; Sept. 18, 2014, PLOS Pathogens, online




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