infective endocarditis Flashcards
what is infective endocarditis?
Infective endocarditis (IE) is the infection of the inner surface of the heart (endocardium), usually the valves.
RF for infective endocarditis?
pathophysiology of infective edncoarditis>
A damaged endocardium can contribute to the development of IE. When part of the endocardium is damaged, the heart valve forms a local blood clot known as non-bacterial thrombotic endocarditis (NBTE). The platelets and fibrin deposits that form as part of the clotting process allows bacteria to stick to the endocardium leading to the formation of vegetations. The valves do not have a dedicated blood supply and so the body is unable to launch an appropriate immune response to the vegetations. The combination of damaged endocardium, vegetation development, and lack of an appropriate immune response results in infective endocarditis.
acute vs subacute vs chronic IE?
Acute IE: patient has signs or symptoms for days up to 6 weeks. Theoretically, a fulminant illness with rapid progression and so is most likely due to S.aureus infection.
Subacute IE: patients has signs or symptoms for 6 weeks up to 3 months.
Chronic IE: patients has signs or symptoms that persist for longer than 3 months.
IE classification via valve type?
Prosthetic-valve endocarditis
Native-valve endocarditis
what is native valve IE?
patient without prosthetic valve implant
what is prostetetic valve IE?
Early prosthetic valve endocarditis occurs within 1 year of surgery. This is usually due to intra-operative contamination or post-operative nosocomial contamination.
Late prosthetic valve endocarditis occurs beyond 1 year of surgery. This is usually due to community-acquired infections.
common causes of IE?
which organism implicated in IE with poor dental hygiene ?
Strep. viridans
which organism implicated in prosthetic valve IE?
Coagulase negative staphylococci e.g. staph. epidermidis
which organism implicated in IE + colorectal cancer?
Strep. bovis
presenting symptoms of IE?
Fever: most common symptom.
Night sweats
Anorexia
Weight loss
Myalgia
Headache
Arthalgia
Abdominal Pain
Cough
Pleuritic pain
systemic signs of IE?
Febrile
Cachectic
Clubbing
Splenomegaly
cardiac signs of IE?
Murmur: fever + new murmur is infective endocarditis until proven otherwise.
Bradycardia: aortic root abscess tracks down to the AVN causing heart block.
vascular features of IE?
Septic emboli: abdominal pain due to splenic infarct/abscess, focal neurology due to stroke, gangrenous fingers.
Janeway lesions: painless haemorrhagic cutaneous lesions in the palms and soles.
immunological features of IE?
Splinter haemorrhages
Osler’s nodes: painful pulp infarcts on end of fingers.
Roth spots: boat-shaped retinal haemorrhages with pale centres seen on fundoscopy.
Glomerulonephritis: identified on urine dip.
what causes immunological features in IE?
immune-complex deposition.
what is the DUKEs criteria for IE?
how do you diagnose IE?
For a definitive diagnosis of IE two major criteria, or one major and three minor criteria, or all five minor criteria must be present.
how many blood cultures needed in IE?
what imaging needed for IE?
what is the minor criteria for IE?
medica mx of IE?
6wks IV abx. start with blind therapy as below:
Native valve: amoxicillin (+/- gentamicin)
Pen-allergy/MRSA: vancomycin (+/- gentamicin)
Prosthetic valve: vancomycin + rifampicin + gentamicin
what abx for Native Valve S. aureus IE?
1st line: flucloxacillin
2nd line: vancomycin + rifampicin
what abx for Prosthetic Valve S. aureus IE?
1st line: flucloxacillin + rifampicin + gentamicin
what abx for Strep viridans IE?
1st line: benzylpenicillin
2nd line: vancomycin + gentamicin
what abx for HACEK IE?
1st line: ceftriaxone
when is surgical mx needed for IE?
Haemodynamic instability
Severe heart failure
Severe sepsis despite antibiotics/failed medical therapy
Valvular obstruction
Infected prosthetic valve
Persistent bacteraemia
Repeated emboli
Aortic root abscess
what is needed for this patient?
PR interval prolongation in a patient with Infective Endocarditis
surgery as it can be secondary to aortic root abscess
complications of IE?
Acute valvular insufficiency causing heart failure
Neurologic complications e.g. stroke, abscess, haemorrhage (mycotic aneurysm)
Embolic complications causing infarction of kidneys, spleen or lung
Infection e.g. osteomyelitis, septic arthritis
