Which organism is commonly associated with subacute infective endocarditis on abnormal valves?

Which organism is commonly associated with subacute infective endocarditis on abnormal valves?

• A. S. viridans
• B. S. aureus
• C. Pseudomonas
• D. Enterococcus faecalis

Answer: (A)

Subacute infective endocarditis on abnormal valves is classically caused by viridans group streptococci, which are part of the normal oral flora. After dental caries or procedures, these bacteria can enter the bloodstream and preferentially adhere to damaged or abnormal valve tissue. They produce dextrans that help them stick to the fibrin-platelet vegetations that form on diseased valves, leading to a slow, indolent infection rather than a rapidly destructive one. This contrasts with Staphylococcus aureus, which more often causes acute endocarditis on previously normal valves and tends to present with a quicker, more aggressive course. While Pseudomonas and Enterococcus faecalis can cause endocarditis in certain settings, they are less characteristically associated with the subacute form on abnormal valves.

Subacute infective endocarditis on abnormal valves is classically caused by viridans group streptococci, which are part of the normal oral flora. After dental caries or procedures, these bacteria can enter the bloodstream and preferentially adhere to damaged or abnormal valve tissue. They produce dextrans that help them stick to the fibrin-platelet vegetations that form on diseased valves, leading to a slow, indolent infection rather than a rapidly destructive one. This contrasts with Staphylococcus aureus, which more often causes acute endocarditis on previously normal valves and tends to present with a quicker, more aggressive course. While Pseudomonas and Enterococcus faecalis can cause endocarditis in certain settings, they are less characteristically associated with the subacute form on abnormal valves.