UK researchers have found another reason for us to keep brushing and flossing our teeth: the same gum bacteria that cause dental plaque can escape from the mouth into the bloodstream and trigger clots that increase risk of heart attack and heart disease.

The study that led to this finding was the work of University of Bristol researchers, in collaboration with scientists at the Royal College of Surgeons in Dublin, Ireland (also called the RCSI) and was presented Monday at the Society for General Microbiology’s autumn meeting that is running from 6-9 September at the University of Nottingham, UK.

Dr Howard Jenkinson, professor of Oral Microbiology at Bristol’s School of Oral and Dental Science, presented the findings at the meeting. He said in a press statement that:

“Poor dental hygiene can lead to bleeding gums, providing bacteria with an escape route into the bloodstream, where they can initiate blood clots leading to heart disease.”

He said we all need to be aware that it’s not only diet, exercise, cholesterol and blood pressure that we should keep an eye on, but it’s also important to have good dental hygiene to reduce our risk of heart problems.

Tooth plaque and gum disease are what happens when Streptococcus bacteria build up in our mouths when we don’t brush and floss regularly. Gum disease makes gums sore and they bleed, allowing the bacteria to get into the bloodstream.

In their study, Jenkinson and colleagues found that once Streptococcus bacteria get into the bloodstream, they use a protein called PadA which sits on their outer surface, to hijack blood platelets and force them to clump together and make blood clots.

Jenkinson described this as a “selfish trick” on the part of the bacteria, which completely encase themselves in a clump of platelets, enabling them to avoid detection by the host immune system, and also, to hide from antibiotics.

“Unfortunately, as well as helping out the bacteria”, explained Jenkinson, “platelet clumping can cause small blood clots, growths on the heart valves (endocarditis) or inflammation of blood vessels that can block the blood supply to the heart and brain”.

The team are now investigating how PadA makes blood platelets clump together so they can find a way to block it. They are doing it with the help of a new blood flow model that mimics the human circulatory system. The model was developed by Dr Steve Kerrigan of RCSI’s School of Pharmacy.

“This could eventually lead to new treatments for cardiovascular disease which is the biggest killer in the developed world,” said Jenkinson.

Dr Damian Walmsley, professor of Restorative Dentistry, in the School of Dentistry at the University of Birmingham, who is also scientific adviser to the British Dental Association, told the BBC that this kind of research is very welcome because it increases understanding of the relationship between gum disease and heart disease.

Walmsley said it also underlines “the high importance of brushing twice a day with fluoride toothpaste, restricting your intake of sugary foods and drinks and visiting the dentist regularly in order to maintain good oral health”.

There are over 100 species and strains of bacteria in the Streptococcus genus, some so diverse they are considered species in their own right.

It wasn’t until advances in genetics, such as genome sequencing, arrived in the lab that scientists were able to see the links among strains in the genus. As more links emerge, the more collaboration ensues between microbiologists who until then had no idea that others in apparently unrelated fields were actually working on the same problems.

Jenkinson is also the organizer of the Streptococcus session of the Society for General Microbiology’s Autumn Meeting, and in his notes about the symposium he wrote that it should not only provide an overview of “this important research field”, but hopefully it will also “re-engage microbiologists working on streptococci and related areas into a UK Streptococcus grouping (UKSTREP) for future benefit”.

“Oral streptococci behaving badly.”
Presented by Howard Jenkinson.
Autumn Meeting of the Society for General Microbiology, 6 September 2010, Nottingham.

Sources: Bristol University, BBC News.

Written by: Catharine Paddock, PhD