Research from Ireland and the UK suggests that people who have bleeding gums from poor dental hygiene and not brushing their teeth regularly could be increasing their risk of heart disease because bacteria in the mouth enter the bloodstream and stick to platelets, leading to blood clots that interrupt the supply of blood to the heart and causing a heart attack.

The study was the work of microbiologists from the University of Bristol in the UK and the Royal College of Surgeons in Ireland, and was presented on 11th September at the Autumn meeting of the Society for General Microbiology in Trinity College, Dublin, Ireland.

A member of the research team, Dr Steve Kerrigan from the Royal College of Surgeons in Dublin said:

“The mouth is probably the dirtiest place in the human body.”

The human mouth harbours up to 700 different types of bacteria, and as Kerrigan explained:

“If you have an open blood vessel from bleeding gums, bacteria will gain entry to your bloodstream. When bacteria get into the bloodstream they encounter tiny fragments called platelets that clot blood when you get a cut. By sticking to the platelets bacteria cause them to clot inside the blood vessel, partially blocking it. This prevents the blood flow back to the heart and we run the risk of suffering a heart attack.”

In the past, such a condition was easy to treat with aggressive antiobiotic therapy, but that option is rapidly disappearing because bacteria are evolving into stronger organisms able to resist many types of anti-microbial drugs.

Another member of the research team, Professor Howard Jenkinson from the University of Bristol, said in a press statement that:

“Cardiovascular disease is currently the biggest killer in the western world. Oral bacteria such as Streptococcus gordonii and Streptococcus sanguinis are common infecting agents, and we now recognise that bacterial infections are an independent risk factor for heart diseases.”

So what they are saying is that you can be fit, slim and eating healthily, but if you don’t look after your teeth, you are still increasing your risk of heart disease.

Jenkinson and colleagues at Bristol University have been looking at how the bacteria interact with blood platelets so that new therapies that target this activity can be developed.

Jenkinson explained that much of the research to date has not investigated how bacteria interact with platelets in conditions that are close to those in the human bloodstream.

“We mimicked the pressure inside the blood vessels and in the heart,” said Jenkinson, which meant that they could show how the bacteria used different ways to make the platelets clump together and completely surround the bacteria. By doing this they can defend themselves in two ways: they can shield themselves against attack by immune cells and also hide from antibiotics.

These findings could explain why antibiotics are not always effective in treating infectious heart disease and emphasize there may be a need to find new drugs to treat the disease.

Jenkinson said he and his team were working to find out the exact spot where the bacteria stick to a platelet, and when they have done this then they can start developing a drug to target that specific area and interaction.

Kerrigan added that they had also found several proteins on the bacteria that appear to help with the clumping. When they deleted the proteins using genetic technology the bacteria were unable to make the platelets clump together, suggesting the proteins were key to this and could be useful targets for drug and vaccine development.

The press statement did not mention if the study is to be published in a journal.

Source: Society for General Microbiology .

Written by: Catharine Paddock, PhD