Q.  A 25 years old gentleman is brought to emergency with the complaint of fever for 7 days. He drinks five units of alcohol per day and admitted to regular intravenous drug abuse. On examination, he is febrile, has tachypnea and tachycardia. Blood pressure is 108/70. JVP is elevated and there is a murmur all over the precordium. What will be most likely cause of infection in this patient?  A. Staphylococcus epidermidis  B. Streptococcus viridans  C. Staphylococcus aureus  D. Pneumocystis carinii    Answer: Staphylococcus aureus   Explanation:  With given history and abuse of i/v drugs, tricuspid valve endocarditis  is most likely diagnosis. Among, i/v drug abusers, Staphylococcus aureus  is most common cause.   
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