types of infective endocarditis

Last reviewed 01/2018

Traditionally, infective endocarditis has been classified into two broad categories according to the pathogenic organism and the clinical presentation:

• acute:
• most often caused by Staphylococcus aureus
• equally prevalent on normal and abnormal valves
• it is rare

• subacute:
• most often caused by Streptococcus viridans
• usually
• affects abnormal valves
• more common

Two specific forms of endocarditis are the infections associated with prosthetic heart valves and intravenous drug abuse:

• prosthetic:
• follows valve replacement
• may present early, within 60 days of valve replacement or late

• right sided endocarditis in intravenous drug abuse:
• accounts for 5% of cases
• tricuspid valve invariably affected
• usually presents acutely in I.V. drug abusers or the immunosuppressed

95% of cases of infective endocarditis effect the left side of the heart, with the mitral and aortic valves affected equally.