Expansion
Vegetations on damaged valves, with embolic and immune complications
Expansion
Organisms
- Staphylococcus aureus: the commonest overall, acute, aggressive, and typical of intravenous drug users (affecting the tricuspid valve) and prosthetic valves
- Streptococcus viridans: subacute, after dental procedures, on previously damaged valves
- Streptococcus gallolyticus (bovis): associated with colorectal carcinoma, so colonoscopy is indicated
- Staphylococcus epidermidis: prosthetic valves
- HACEK organisms, and culture-negative causes such as Coxiella and Bartonella
Valves: mitral most often, then aortic; tricuspid in intravenous drug users because it is the first valve encountered by injected organisms.
Complications
- Embolic: stroke, splenic and renal infarcts, mycotic aneurysm, Janeway lesions (painless palmar macules)
- Immune complex: Osler nodes (painful finger pulp nodules), Roth spots, glomerulonephritis, splinter haemorrhages
- Local: valve destruction with regurgitation, abscess, heart block
Diagnosis uses the modified Duke criteria, combining blood cultures and echocardiographic evidence with minor criteria.