Recent research has revealed that common oral bacteria, specifically viridans streptococci, can form protective biofilms inside atherosclerotic plaques in coronary arteries. These hidden bacterial communities may remain undetected by the immune system until plaque rupture triggers a heart attack. This discovery adds a new dimension to the understanding of coronary artery disease beyond traditional risk factors such as cholesterol, hypertension, diabetes, and smoking.
Role of Viridans Streptococci in Coronary Arteries
Viridans streptococci are oral bacteria commonly found in dental plaque. The bacteria form biofilms deep within the lipid-rich cores of atherosclerotic plaques. These biofilms protect the bacteria from immune detection and antibiotic treatment. In ruptured plaques, the bacteria relocate to the plaque’s outer layer, activating immune receptors like toll-like receptor 2 (TLR2), which may trigger inflammation and rupture.
Study Methodology and Findings
The study analysed coronary artery samples from 121 sudden-death autopsies and 96 vascular surgery patients using DNA tests and microscopic staining. Bacterial DNA was present in number of samples, with viridans streptococci detected in about 42%. Controls ruled out contamination, confirming the bacteria’s genuine presence within plaques. This suggests bacterial biofilms persist silently in arteries for years.
Implications for Treatment
Previous antibiotic treatments for coronary disease have failed, likely because biofilms shield bacteria from drugs and immune cells. This discovery suggests new treatment approaches are needed. One proposal is preventive antibiotic therapy for high-risk individuals, similar to strategies used for rheumatic fever. However, such ideas remain speculative pending further research.
Connection Between Oral Health and Cardiovascular Disease
Oral bacteria can switch between stable biofilms and invasive free-floating forms. Changes in the oral environment or blood vessel lining may allow bacteria to enter arteries and cause infections such as infective endocarditis. Epidemiological studies show good oral hygiene reduces stroke and heart disease risk. Untreated gum disease and dental infections correlate with increased cardiovascular problems.
Public Health and Preventive Measures
In countries like India, where cardiovascular disease affects younger populations and oral disease is widespread, educating the public about the mouth-heart link is vital. Regular dental care, early gum disease treatment, and collaboration between dentists and cardiologists are essential. Oral swab screening after age 40 could help identify high-risk individuals if validated by further research.
Future Research Directions
The Finnish research team plans to publish comprehensive genetic sequencing of bacteria in coronary plaques. They also aim to explore vaccines targeting bacterial biofilm formation and related clotting processes. Such advances could transform coronary artery disease management by addressing hidden bacterial factors alongside traditional risk controls.
Questions for UPSC:
- Point out the role of biofilms in bacterial resistance to antibiotics and immune responses, with suitable examples from medical microbiology.
- Underline the changes in public health strategies required to integrate oral hygiene and cardiovascular disease prevention in India.
- Critically analyse the impact of chronic infections on non-communicable diseases, especially cardiovascular diseases, with examples from global health studies.
- Estimate the potential benefits and challenges of developing vaccines against bacterial biofilms in managing coronary artery disease.
