<prompt> Organism leading to infective endocarditis?Staph aureusKlebsiellaStreptococcus PneumoniaeMeningococcus  <response>: Ans. a Staphylococcus aureusRef: Harrison 19th ed. 816 Overall S.Aureus infection is the most common cause of IE, including Prosthetic Valve Endocarditis, acute Infective Endocarditis, and IVDA Intravenous drug Abuse Infective Endocarditis. Approximately 35-60.5 of staphylococcal bacteremias are complicated by IE. More than half the cases are not associated with underlying valvular disease. The mortality rate of S aureus IE is 40-50. The incidence of MRSA infections, both the hospital- and community-acquired varieties, has dramatically increased 50 of isolates. Sixty percent of individuals are intermittent carriers of MRSA or MSSA. 