Endocarditis Flashcards
What is the definition of endocarditis?
Infection of the endocardium with formation of a vegetation resulting in damage to the cusps of valves
What is quorum sensing?
Ability of an organism to produce chemical messengers to attract other bacteria
What are some of the gram positive bacteria which cause endocarditis
- Gram positive rods,
- Staphylococci: Coagulase negative staphylococci or staph. aureus (methicillin resistant/sensitive)
- Streptococci: Strep viridans (oral flora) or enterococci
What are the gram negative causes of endocarditis?
- Enterobacteriales (E.coli)
- Pseudomonas aeruginosa
- HACEK organisms
- Coxiella burnetii (Q fever)
What fungi species can cause endocarditis
Candida species
What are the different classifications of endocarditis?
- Native valve endocarditis (NVE)
- Endocarditis in IV drug users
- Prosthetic valve endocarditis
What are the most common causative organisms for the different classes of endocarditis
- NVE: S. viridans
- IV drug users: S. aureus
- Prosthetic valve endocarditis: CoNS
What are the risk factors for native valve endocarditis?
- Underlying valve abnormalities (aortic stenosis or mitral valve prolapse)
- Common causes for aortic stenosis is age related calcification, calcification of congenitally abnormal valve and rheumatic fever.
Explain the pathogenesis of rheumatic fever
- Commonly caused by a streptococcus pyogens infections. The strep has M proteins which result in the formation of anti M antibodies. However M proteins are genetically similar to cardiac valves thus causing an autoimmune attack. This can result in a stenosis or regurgitation.
What is the common valve affected in IVDU endocarditis and what are the different presentations?
- Tricuspid valve
- Acute: toxic presentation with progressive valve destruction and metastatic infection. Commonly caused by S.aureus.
- Subacut : Mild toxicity with presentation occuring over weeks to months. Rarely leads to metastatic infection. Commonly caused by strep.viridans or enterococcus
What are the early manifestations of endocarditis?
- Incubation period of around 2 weeks
- Presents with fever and new murmur (think IE!) however murmur is absent in tricuspid endocarditis
- fatigue and malaise
What are some of the embolic events in endocarditis
- Small emboli which can cause petechiae, splinter haemorrhages, haematuria.
- Large emboli which can cause a CVA or renal infarction
- Right sided endocarditis can cause a septic pulmonary emboli.
What are some of the long term effects of endocarditis?
- Osler’s nodes which are painful palpable lesions found on the hands and feet.
- Immunological reactions which can cause splenomegaly. nephritis, vasculitis lesions of the skin and eye, clubbing.
-Tissue damage which can cause valve destruction or valve abscess
What should make you think infective endocarditis?
- ALL patietns with S.aureus bacteraemia
- IV drug users with ANY positive blood culture,
- All patients with prosthetic valves and positive blood culture
How is the diagnosis of endocarditis made?
- 3 sets of blood cultures with 10mls/bottle, before antibiotics and with aseptic technique
- Echocardiogram (transoesophageal is more sensitive but more invasive)
