New research supports the well understood link between heart disease and the oral microbiome, revealing that oral microbes could directly contribute to heart attacks.
Researchers at Tampere University in Finland, writing in the Journal of the American Heart Association (JAHA) found DNA from viridans streptococci – bacteria commonly found in the mouth – in 42% of arterial plaque samples of patients that had suffered cardiac issues. These bacteria were not only found as contaminants, but had formed biofilms that embedded within the plaque, disguised from and posing a threat to the immune system, causing inflammation and rupture.
The idea of infection being involved with heart disease is well established. Pekka J. Karhunen MD PhD, a professor in the Faculty of Medicine and Health Technology at Tampere University in Finland explains that: “The possibility that infectious agents are involved in the chronic inflammation of coronary plaques has been considered for a long time, but this theory was abandoned about 20 years ago due to failed large long-term antibiotics trials.
He explains the reason for the reintroduced research, explaining that: “The interest has now been renewed due to the development of molecular microbiological methods that enable the identification of bacterial DNA even in small amounts of biological specimens.”
The study analysed coronary plaque samples from 121 people that had died from sudden cardiac death and 96 people who had undergone endarterectomy – a surgery to clear plaque from the arteries.
From this, bacterial DNA was detected in 65% of post-mortem plaque samples and 58% of surgical samples. With the majority containing oral bacteria – in particular viridans streptococci – it appears that microbes can migrate from the mouth into the bloodstream and wedge into the arteries.
“Oral viridans group streptococci are known to act as early colonisers in the build-up of the dental biofilm known as dental plaque. This signals that the streptococci may not be there alone” explains Karhunen.
“It is possible that there is a biofilm composed of many bacteria… the bacteria are safe inside the jelly-like cover and they do not cause any harm to the individual” he describes.
While the findings are intriguing medical specialists around the world, experts advise caution. Cardiologist Yu-Ming Ni warns: “I would be cautious to just go and make the assumption that these bacteria are definitely the reason for plaque disruption,” he said.
The intersection discovered in this study adds to long-growing evidence that oral health and cardiovascular health are interconnected – something which could lend explanation to why patients with periodontitis or poor oral hygiene routines face a higher risk of heart complications.
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