infective endocarditits Flashcards
what is the pathophysiology of infective endocarditis ?
endocardium is damaged due to turbulent blood flow
causes a platelete-fibrin deposition
transient bacteriemia
adherence of bacteria to blood clot
multiplication of the bacteria to cause a vegetation
parts of the vegetation embolises
immunological stimulation forms immune complexes
what are the predisposing factors of infective endocarditis ?
- damaged valves/turbulent blood flow such as with atherosclerotic heart disease
- transient bacteremia as with intravenous drug abusers
can infective endocarditis happen to a normal valve ?
yes as with the cases of staph aureus in an immunocompromised patient
what is the course of symptoms in infective endocarditis ?
insidious but can be acute
what are the main presenting symptoms of IE ?
fever is present in more than 95% of patients fatigue shortness of breath nausea myalgia
what are the signs of IE?
fever pallor new or changing murmur right or left ventricular failure hepatomegaly/splenomegaly emboli sequela oslers nodes, splinters
what are the peripheral stigmata of IE?
Roth spots, Osler nodes, Janeway lesions, and splinter hemorrhages
what are the vascular complications of IE?
embolic lesions originating from the vegetations
mycotic aneurysms that could cause obstructions anywhere
when are immunological sequelae more commonly seen ?
in subacute presentations of IE
what are the complications of the immunological sequale?
immune mediated vasculitis:
glomerulonephritis
oslers nodes
splinter haemorrhages
what are the classifications of IE ?
divided into native valve and prosthetic valve
how do we differentiate between an early and a late prosthetic valve ?
less than 6 months from insertion
more than 6 months from insertion
which valve is most likely to affected with IVDU ?
tricuspid valve
what is the most common causative organism with native valve endocarditis ?
viridans streptococci
staphylococcus aureus
could possibly be culture negative
where does viridans streptococci exist ?
normal flora of the oropharynx
gut flora
what kind of hemolysis happens with viridans streptococci and what gram stain is it ?
alpha hemolysis ( partial hemolysis )
gram positive in long chains
what are HACEK group of organisms ?
gram negative organisms
difficult to grow
difficult to treat
what are the causes of culture negative infective endocarditis in native valves ?
HACEK organisms
previous antibiotic therapy
Candida spp.
fastidious streptococci
how can you make a diagnosis of culture negative infective endocarditis ?
prolonged cultures and fungal cultures
serology - paired sera
serology - paired sera
when is prosthetic valve endocarditis highest risk ?
first 2 months following the procedure
what are the causative organisms of early prosthetic valve endocarditis ?
( first 6 months)
s.aureus
coagulase negative staphylococci e.g staphylococcus epidermidis
what are the causative organisms of late prosthetic valve endocarditis ?
viridans streptococci
staph. aureus
how do you make a diagnosis of prosthetic valve endocarditis ?
blood culture is the most important investigation
Echocardiogram ( trans-oesophageal and trans thoracic)
what are the specific steps required to collect a blood sample for culture ?
collect at least 2 sets , ideally 3 before the start of therapy
collect them over a 1-2 hour period in acutely ill patients but in a longer period in more stable patients
what is the criteria for diagnosing infective endocarditis ?
Modified duke’s criteria
what are the major criteria in modified duke’s criteria ?
1- positive blood cultures or organisms seen in histology ( 2 separate samples , only one if thee organism is coxiella )
2- evidence of myocardial involvement on echo
3- new valvular regurgitation
what are the minor criteria in duke’s modified criteria ?
-predisposition or IV drug abuse
-fever
-vascular :
septic pulmonary infarction
intracranial haemorrhages
-immunological:
glomerulonephritis ( microscopic hematuria )
osler’s nodes ( tender nodules )
splinters
-serology:
coxiella burnetti
how many of each of the criteria is required to make a diagnosis of IE?
to make a definitive diagnosis of IE :
2 major
or
1 major and 3 minor
or
all 5 minor
what are the requirements to make a possible diagnosis of IE ?
1 major and 1 minor or 3 minor
3 minor
what medical treatment would be given to an IE patient generally ?
high dose, regular and intravenous empirical antibiotics after peripheral blood sampling
which antibiotics are given with native valves ?
amoxicillin and gentamicin
which antibiotics are given with prosthetic valves ?
vancomycin and gentamicin
what must be monitored and measured after giving antibiotics to IE patient ?
Measure minimum inhibitory concentration (MIC)
what to give for streptococcal endocarditis involving a native valve that is penicillin sensitive ?
7.2g of penicillin in 6 individual doses
IV gentamicin 80 mg for 2 weeks
IV gentamicin 80 mg for 2 weeks
what to give for staphylococcal endocarditis for MSSA and MSSE ?
MSSA: staph aureus
MSSE : staph epidermidis
fluxocallin 12g daily and IV gentamicin
what to give for staphylococcal endocarditis for MRSA and MRSE ?
vancomycin and gentamicin or rifampcin for a duration of 4-6 weeks
when would we consider a patient for surgery?
1- if the patient develops heart failure or persistent fever or recurrent embolism
2- presence of large vegetations
3- intracardiac abscess
4- acute valvular regurgitation with pulmonary oedema
4- dehiscence of a prosthetic valve
5- infection with candida or coxiella , refractory enterococcal endocarditis
what are the preventative measure to take to avoid infective endocarditis ?
1- aseptic techniques for operations
2- dental care prior to valve operations
what is the is the most sensitive diagnostic test for IE ?
TOE
what can be seen on ECG of a patient with infective endocarditis that serves as an indication for surgery?
PR interval prolongation , which indicates aortic root abscess formation
streptococcus bovis ?
can cause both infective endocarditis and colorectal cancer
what is the posterior relation and superior relation of the left atrium ?
posterior: oesophagus
superior : pulmonary trunk
what type of emboli are associated with right sided lesions ?
septic pulmonary emboli
what type of emboli is associated with left sided lesions ?
may embolize to any tissue
