Coagulase-negative S. aureus: causes subacute disease similar to Streptococcus viridans. Accounts for 30% of IE associated with prosthetic valves. Streptococci: S. viridans: 50-60% of subacute IE cases. Group D streptococci: usually subacute and the third most common cause of IE. Streptococcus intermedius: acute and subacute infection. Causes 15% of all cases of IE. Group A, C and G streptococci: acute IE is similar to that with S. aureus. High mortality (up to 70%).