<prompt> Most common cause and the most common valve affected in Infective endocarditis in I.V drug abusersStreptococcus viridanstricuspid valvePseudomonasmitral valveStaphylococcus aureustricuspid valveStreptococcus bovismitral valve  <response>: In I.V drug abusers it is staph.aureus to cause Infective endocarditis most commonly and the right sided valves are more commonly affected than the left sided valves 