Study reveals why common pneumonia is so deadly:
Many experts assumed that inflammation killed patients. As with any bacteria or virus, the body’s immune system activates to repel the invader, but in some patients this reaction becomes too strong and can itself be fatal.“Many patients die at a very early time point — 48 hours or so, but less than 72 hours. People noticed this but they didn’t know why,” Li said.
His team studied the bacteria, first in lab dishes and then in mice. They looked specifically at a toxin known to be produced by the bacteria, called pneumolysin.
It was known to lyse, or break open cells, but Li’s team found this also caused widespread bleeding in lung tissue.
Tests on tissue taken from human patients who died confirmed this.
“When you look at the pathology of the lung, we found bleeding everywhere in the lung. That is a key point,” Li said.
And antibiotics kill bacteria by cutting them open, which releases even more pneumolysin.