Context: A recent study conducted by researchers at Tampere University, Finland, has revealed a surprising connection between oral bacteria and heart attacks. The study examined coronary arteries from 121 sudden-death autopsies and found that Viridans streptococci were present in about 42% of both autopsy and surgical cases, making them the most frequently detected bacterial species.
About Viridans Streptococci
Viridans streptococci are a group of gram-positive cocci commonly found in the oral cavity, but also present in the gastrointestinal, respiratory, and female genital tracts. Normally harmless, they are part of the body’s commensal microbiota.
However, under certain conditions, they can turn pathogenic, being a leading cause of infective endocarditis (IE) — an infection that affects the inner lining of the heart, especially in individuals with previously damaged cardiac tissue.
Viridans Streptococcal Biofilm Formation
The bacteria have the ability to form biofilms — sticky, protective layers that allow them to adhere to surfaces such as atherosclerotic plaques (fatty buildups inside arteries).
Within these biofilms, bacteria remain hidden from the immune system, enabling them to persist undetected for long periods.
Link Between Oral Bacteria and Heart Disease:
The study highlights how biofilm-forming Viridans streptococci can play a direct role in triggering heart attacks:
- Biofilm Stability: The bacteria remain embedded deep within arterial plaques, shielded from immune response.
- Biofilm Disruption: Over time, fragments of the biofilm can break loose.
- Inflammation Trigger: When released, these bacteria provoke inflammation in the arterial wall, weakening the fibrous cap that covers the fatty plaque.
- Plaque Rupture: The weakened cap eventually ruptures, leading to clot formation, which can block blood flow and cause a heart attack.
Significance of the Study:
The findings underscore the link between oral health and cardiovascular health, suggesting that oral bacteria may be silent contributors to heart disease.
The presence of Viridans streptococci in coronary plaques demonstrates the importance of maintaining good oral hygiene to reduce systemic inflammation and cardiac risk.
Conclusion
The Tampere University study provides crucial evidence that the mouth-heart connection is not merely coincidental but biologically plausible.
By forming biofilms within arterial plaques, Viridans streptococci act as hidden players in the development of atherosclerosis and heart attacks — highlighting how preventive dental care may play an unexpected role in cardiovascular protection.