A 58-year-old man with known rheumatic mitral valve disease develops 4 weeks of low grade fever, malaise, and weight loss following a recent dental extraction. Blood cultures grow alpha-hemolytic streptococci. Which organism is most likely responsible?
- A Streptococcus pyogenes
- B Viridans group streptococci ✓
- C Enterococcus faecalis
- D Staphylococcus lugdunensis
Correct answer: B. Viridans group streptococci
Explanation
Subacute infective endocarditis on a previously damaged valve follows indolent courses over weeks, and viridans group streptococci entering via dental procedures are the classic cause. Enterococci follow genitourinary or gastrointestinal instrumentation, Staphylococcus aureus causes aggressive acute disease even on normal valves, and pyogenes is not an endocardial pathogen of this pattern.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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