Endocarditis Flashcards
Define endocarditis [1]
Infection of endocardium (lining of heart) leading to the formation of a vegetation which results in damage to cusp of valves
What is a vegetation? [1]
An abnormal outgrowth from a membrane found on the membrane lining the heart valves
What is the vegetation composed of? [5]
- fibrin mesh
- platelets (which adhere to fibrin mesh)
- white blood cells
- RBC debris
- infective organisms (which are trapped within the glue-like substance)
Which valves are commonly affected by infective endocarditis? [3]
- mitral valve → most commonly affected
- aortic valve → 2nd most common site
- tricuspid valve → 3rd most common site
- most common site in IV drug users (IVDU)
Define quorum sensing [1]
Cell communication that is widely used by bacterial pathogens to coordinate the expression of several collective traits, including the production of multiple virulence factors, biofilm formation, and swarming motility once a population threshold is reached.
What are the 3 types of infective endocarditis? [3]
- native valve endocarditis (NVE)
- endocarditis in IVDUs (IVDU IE)
- prosthetic valve endocarditis (PVE)
What are the most common microbiological causes of native valve endocarditis? [1]
streptococcus viridians
What are the most common microbiological causes of IVDU infective endocarditis? [3]
- staphylococcus aureus
- gram negative organisms
- fungi
What are the most common microbiological causes of prostatic valve endocarditis? [3]
- coagulase-negative staphylococci (CoNS)
- gram negative organisms
- fungi
Who is more susceptible to infective endocarditis? Males or females? [1]
males
What are the risk factors of native valve endocarditis? [4]
- underlying valve abnormalities
- aortic stenosis
- mitral valve prolapse (MVP)
- IVDU
- no risk factors in 30% of cases
Why are IV drug users (IVDU) more susceptible to right-sided endocarditis (i.e. IE in tricuspid valve)? [4]
due to a combination of factors:
- particulate-induced endothelial damage to right-sided valves
- increased bacterial loads in these patients
- direct physiologic effects of the injected drugs
- deficient immune response caused by IVDU
What are the general clinical features of acute infective endocarditis? [3]
- toxic presentation (patient presents very unwell)
- progressive valve destruction & metastatic infection developing in days to weeks (rapidly)
- i.e. septic emboli fly off from the vegetation to other parts of the body
What is the most common cause of acute IE? [1]
S. aureus
What are the general clinical features of subacute infective endocarditis? [3]
- mild toxicity
- presents indolently over weeks to months in an insidious manner
- rarely leads to metastatic infection
What are the common causes of subacute IE? [2]
- Strep. viridans (most commonly)
- enterococcus species
How long can IE take to present? [3]
- typically around 2 weeks
- PVE can take longer to present
- some organisms (e.g. strep. viridian) can present more slowly over months
What are the 2 typical presenting symptoms of IE in the early stages and in what occasions can these symptoms be absent? [4]
- fever
- may be absent in elderly
- murmur
- often absent in tricuspid endocarditis
What are the 2 hallmarks of embolic disease in IE? [2]
- splinter haemorrhages
- conjunctival petechiae
What are conjunctival petechiae? [1]
red or purple spots on the skin or conjunctiva caused by a minor bleed from broken capillary blood vessels
What are the complications of small emboli caused by IE? [3]
- petechiae
- splinter haemorrhages
- haematuria
What are the complications of large emboli caused by IE? [2]
- stroke (CVA)
- renal infarction
How does right sided endocarditis typically present? [3]
- septic pulmonary emboli, which results in…
- pleuritic chest pain
- classical CXR appearance (see image)
Define pleuritic chest pain [1]
sudden and intense sharp, stabbing, or burning pain in the chest when inhaling and exhaling
What is this? [3]
- osler’s nodes
- painful palpable lesions
- found on hands and feet
What are the long-term effects of infective endocarditis? [6]
- immunological reaction
- splenomegaly
- nephritis
- vasculitis lesions of skin & eye
- clubbing
- tissue damage
- valve destruction
- valve abscess
When should you consider diagnosing IE? [3]
- all patients with S. aureus bacteraemia (SAB)
- IVDU with any positive blood cultures
- all patients with prosthetic valves and positive blood cultures
How should you take blood cultures for IE? [3]
- 3 sets of blood cultures should be taken from different sites
- do not wait for fever before taking blood cultures as there is a constant bacteraemia in IE
- should be taken before antibiotics are given
What are the 2 types of echocardiograph? [2]
- transthoracic (TTE)
- transoesophageal (TOE)
What are the features of transthoracic echo (TTE)? [5]
- non-invasive
- transducer is placed at front of chest
- easy to perform
- 50% sensitivity
- performed first
- if negative but still a high clinical suspicion remains, a TOE is indicated
What are the features of a transoesophageal echo (TOE)? [5]
- invasive
- transducer placed in oesophagus
- may require sedation
- 85-100% sensitivity
- better in detecting smaller vegetations
What is the Duke Criteria for diagnosing IE? [3]
- 2 major (or)
- 1 major + 3 minor (or)
- 5 minor criteria fulfilled
What are the major criteria for diagnosing IE according to the Duke Criteria? [2]
- typical organism detected in 2 separate blood cultures
- positive echocardiogram or new valve regurgitation
What are the minor criteria for diagnosing IE according to Duke Criteria? [5]
- predisposition (heart condition or IVDU)
- fever >38°C
- vascular phenomena (e.g. septic emboli)
- immunological phenomena (e.g. olser’s nodes)
- 1 positive blood culture
Bactericidal antibiotics are usually used in high doses for curing IE. What is the difference between a bactericidal antibiotic and a bacteriostatic antibotic? [2]
- bactericidal agents = actively kill organisms
- bacteriostatic agents = inhibit growth of organisms, allowing the immune system to mount a lethal response
How long is antimicrobial therapy typically given for native valve endocarditis (NVE)? [1]
4 weeks
How long is antimicrobial therapy typically given for prostatic valve endocarditis (PVE)? [1]
6 weeks
The antimicrobial treatment given is typically tailed to organism’s susceptibility. What therapies are typically given for the Streptococcus species? [2]
benzylpenicillin +/- gentamicin
The antimicrobial treatment given is typically tailed to organism’s susceptibility. What therapies are typically given for the Enterococcus species? [3]
amoxicillin or vancomycin
+/- gentamicin
The antimicrobial treatment given is typically tailed to organism’s susceptibility. What therapies are typically given for the S. aureus (MSSA)? [2]
flucloxacillin +/- gentamicin
The antimicrobial treatment given is typically tailed to organism’s susceptibility. What therapies are typically given for the S. aureus (MRSA)? [2]
vancomycin +/- gentamicin
The antimicrobial treatment given is typically tailed to organism’s susceptibility. What therapies are typically given for CoNS? [3]
vancomycin +/- gentamicin +/- rifampicin
What are the indications for surgical intervention? [3]
- heart failure
- uncontrollable infection
- prevention of embolism
What are the signs & symptoms of an uncontrollable infection requiring surgical intervention? [6]
- abscess
- false aneurysm
- enlarging vegetation
- persisting fever + positive blood cultures >7 to 10 days
- infection caused by multi-drug resistant organisms
