CHICAGO – A pneumonia caused by bacterial infections represents a much greater threat to the heart than lungs caused by viral infections, a new study suggests.
Patients in a study with a diagnosis of bacterial pneumonia had a higher risk of heart attack, stroke or death, compared with patients diagnosed with viral pneumonia, researchers said.
The findings were presented today (November 11th) at the annual meeting of the American Heart Association. The study has not yet been published in the journal. [27 Devastating Infectious Diseases]
Both bacteria and viruses can cause pneumonia, an infection characterized by inflammation in air bags of the lungs.
In a survey, researchers reviewed data from 2007 to 2014 to around 4,800 patients in a hospital in Utah, diagnosed with pneumonia and hospitalized. About 80 percent of patients are diagnosed with bacterial pneumonia. The researchers then examined the data about those patients within 90 days of their diagnosis, specifying which patients had suffered a stroke, stroke, heart failure, or death. (The researchers followed patients for 90 days, as previous studies show that the risk of these complications increases 90 days after the diagnosis of the lungs.)
The researchers found that 34 percent of patients with bacterial pneumonia had the main complication of the heart in that 90-day window, compared with 26 percent of patients with a diagnosis of viral pneumonia.
So, why should a bacterial version pose a greater threat to the heart? This difference is most likely because bacterial pneumonia causes more inflammation in the arteries – a risk factor for heart disease – than viral pneumonia, says the senior author Dr. Josef Brent Muhlestein, a cardiologist at the Intermountain Heart Institute in Utah.
Bacteria and viruses infect the body in various ways, Muhlestein told Live Science: Viruses enter cells and cause damage, while bacteria stay out of the cells and release toxins into the bloodstream. The second mechanism causes more inflammation in the blood, which can cause damage to arteries.
Moreover, bacterial pneumonia often causes more problems, higher levels of bloodthirsty markers and a high number of white blood cells, Muhlestein said. (A high number of white blood cells indicate that the body is fighting infection.) However, in addition, the symptoms of viral and bacterial pneumonia are not so different – and most of the time doctors presume that the infection is bacterial and begin to treat the antibiotic patient, he added .
Nevertheless, Muhlestein noticed that they were surprised by the findings. Previous research has shown that people with underlying health conditions who receive flu are much less likely to have a heart attack next year, compared to those who do not get flu. "So, in my opinion, I was thinking, so maybe they are viral infections [such as the] flu [are] worse for heart complication than bacterial infection – but that's not what we found. "
In any case, "if you are ill, you should go to a doctor," he said. Indeed, the study found that "people who have viral pneumonia continue to have heart complications – just not so much" as people with bacterial pneumonia.
Muhlestein said that he also recommended that doctors prescribe antibiotics for older people with health problems, even if they think the infection is viral. This is because these individuals have a weaker immune system and can easily develop a bacterial infection that can progress to pneumonia, he said.
Originally published on Live Science.