Dental plaque bacteria may trigger blood clots
Oral bacteria that escape into the bloodstream are able to cause blood clots and trigger an infection of the inner lining of the heart, say researchers from the Royal College of Surgeons in Ireland and the University of Bristol. The finding lends further credence to the importance of brushing and flossing “to keep these bacteria in check,” said Helen Petersen, Ph.D., of the University of Bristol who presented the research at the Society for General Microbiology’s spring conference in Dublin in March.
Endocarditis can damage or destroy heart valves and lead to life-threatening complications. The condition occurs when bacteria or other germs from another part of your body—such as the mouth—spread through the bloodstream and attach to damaged areas in the heart.
Streptococcus gordonii is a normal inhabitant of the mouth and contributes to plaque that forms on the surface of teeth. But if the bacteria enter the bloodstream through bleeding gums, they can start to wreak havoc by masquerading as human proteins.
The researchers discovered that S. gordonii is able to produce a molecule on its surface that lets it mimic the human protein fibrinogen—a blood-clotting factor. This activates the platelets, causing them to clump inside blood vessels. The unwanted blood clots encase the bacteria, protecting them from the immune system and from antibiotics that might be used to treat infection. Platelet clumping can lead to growths on the heart valves (endocarditis), or inflammation of blood vessels that can block the blood supply to the heart or brain.
A better understanding of the relationship between bacteria and platelets could ultimately lead to new treatments for infective endocarditis, the researchers said.
“In the development of infective endocarditis, a crucial step is the bacteria sticking to the heart valve and then activating platelets to form a clot,” said Dr. Petersen. “We are now looking at the mechanism behind this sequence of events in the hope that we can develop new drugs which are needed to prevent blood clots and also infective endocarditis.”
Infective endocarditis is treated with surgery or strong antibiotics, which is becoming more difficult with growing antibiotic resistance.
“About 30 percent of people with infective endocarditis die and most will require surgery for replacement of the infected heart valve with a metal or animal valve,” said Dr. Petersen.
“Our team has now identified the critical components of the S. gordonii molecule that mimics fibrinogen, so we are getting closer to being able to design new compounds to inhibit it,” said Steve Kerrigan, Ph.D., from the Royal College of Surgeons in Ireland. “This would prevent the stimulation of unwanted blood clots.”
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