Viridans streptococci
Why in news?
Recent research from Tampere University in Finland highlights significant findings about Viridans streptococci related to heart disease.
About Viridans streptococci
- Viridans streptococci are a large group of alpha-hemolytic, Gram-positive cocci bacteria
- Theas are commonly found as part of the normal flora in the human oral cavity, as well as the gastrointestinal, respiratory, and female genital tracts.
- They produce a greenish coloration on blood agar due to alpha-hemolysis, hence the name "viridans" (Latin for green).
- These bacteria do not have Lancefield antigens and are generally of low pathogenicity in healthy individuals.
How Viridans streptococci can lead to heart attacks ?
- Viridans streptococci are oral bacteria that can enter the bloodstream through oral trauma or dental procedures and adhere to damaged heart tissue or atherosclerotic plaques.
- These bacteria have the ability to form biofilms—sticky protective layers—that allow them to persist hidden deep inside arterial plaques.
- The biofilms enable Viridans streptococci to evade the immune system and survive in the plaques for long periods.
- Over time, fragments of these biofilms can break loose, triggering inflammation in the arterial wall.
- This inflammation weakens the fibrous cap covering the fatty plaque within the coronary arteries.
- The damaged cap can rupture, leading to clot formation which can block blood flow, causing a heart attack.
- Viridans streptococci are also a major cause of infective endocarditis, especially on previously damaged valves, leading to complications that may also influence cardiovascular events.
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