Most common cause of acute bacterial endocarditis is: September 2009

Ans. A: Staphylococcus aureus Overall, S aureus infection is the most common cause of Infective Endocarditis (IE), including acute IE, and Intravenous drug abusers IE. More than half the cases are not associated with underlying valvular disease. Streptococcus viridans accounts for approximately 50-60% of cases of subacute disease. Most clinical signs and symptoms are mediated immunologically. Streptococcus intermedius group infections may be acute or subacute. S intermedius infection accounts for 15% of streptococcal IE cases. S intermedius is unique among the streptococci; it can actively invade tissue and can cause abscesses.