A 23 year old patient had fever since 2 weeks presents with mitral valve vegetation. Patient is a intravenous drug abuser. Most common cause of endocarditis in this patient is :
i.v. drug abusers

Lt. sided endocarditis – Enterococcus
Rt. sided endocarditis – S.aureus
S.aureus
S.epidermidis
Enterococcus
Viridans Streptococci