Infective endocarditis Flashcards
What is infective endocarditis (IE)?
Refers to the infection of the inner surface of the heart (endocardium), usually the valves.
How is infective endocarditis (IE) classified?
It can be classified into:
- acute (6wks of symptoms/signs)
- subacute (6 wks-3 months)
- chronic (>3 months)
It can also be classified according to the type of valve involved:
- native-valve endocarditis (no prosthetic valve implant)
- prosthetic-valve endocarditis
Risk factors for infective endocarditis?
IV drug use
CKD (especially on dialysis)
Immunocompromised (e.g. cancer, HIV, immunosuppressive medications)
Hx of IE
Structural pathology:
- valvular heart disease
- congenital heart disease
- hypertrophic cardiomyopathy
- prosthetic heart valve
- implantable cardiac devices (e.g. pacemakers)
What organisms causes infective endocarditis (IE)?
Staphylococcus aureus (most common; coagulase positive)
Streptococcus viridans (most common in pts with poor dental hygiene)
Enterococcus
Staphylococcus epidermidis (causes prosthetic valve endocarditis)
Streptococcus bovis (links with colorectal cancer)
HACEK organisms (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella)
How does a damaged endocardium contribute to the development of infective endocarditis?
When part of the endocardium is damaged, the heart valve can form a local clot (aka non-bacterial thrombotic endocarditis -NHTE).
Platelet and fibrin deposits cause bacteria to stick to the endocardium, forming masses (vegetations) on the endocardium.
Valve do not have a dedicated blood supply, so it can’t have an appropriate immune response, hence it results in infective endocarditis.
How can bacteria enter the system?
Dental tx
Genitourinary tract
Cardiac surgery
IV drug abuse
What symptoms are present in infective endocarditis?
Acute -rapid deterioration
Subacute/chronic -non-specific symptoms
Fever
Night sweats
Anorexia
Weight loss
Myalgia
Headache
Arthalgia
Abdominal Pain
Cough
Pleuritic pain
What signs are present in infective endocarditis?
Febrile
Cachectic
Clubbing
Splenomegaly
Murmur
Bradycardia
Septic emboli
- abdominal pain
- focal neurology due to stroke
- gangrenous fingers
Splinter haemorrhages
Osler’s nodes
Roth spots (haemorrhages on the retina seen during fundoscopy)
Glomerulonephritis (on urine dip)
How to distinguish acute and subacute infective endocarditis?
Acute
- cause: staphylococcus aureus
- happens in healthy hearts
- can rapidly progress and lead to sepsis
Subacute
- cause: streptococcus viridans
- happens in pre-existing heart disease
- delayed symptoms over several wks to months
- after tx, rarely leads to severe cardiac damage
What IVx would you do for infective endocarditis?
ECG
- prolongation of PR interval
- worsening of aortic root abscess
Urine dip
- haematuria (glomerulonephritis)
Blood cultures
- 3 samples taken at different times and sites
Routine bloods
- inflammatory markers
- FBC (normocytic anaemia in subacute/chronic)
Echocardiogram (1st line)
Transthoracic echocardiogram (2nd line)
CT CAP (septic emboli)
What is Duke criteria for infective endocarditis?
Must have 2 major criteria OR 1 major and 3 minor criteria OR all 5 minor criteria present.
BE FIVE PM
Major Criteria:
Blood Cultures
- 2 separate +ve cultures
- 2 +ve blood cultures >12 hours apart or =>3 positive blood cultures with less specific microorganisms (S.aureus or S. epidermidis)
- single +ve Coxiella burnetti or positive antibody titre
Evidence of Endocardial Involvement
- echocardiogram (TTE, then TOE) -vegetation, abscess, new valvular regurgitation, partial dehiscence of prosthetic valve
- Paravalvular lesions on cardiac C
Minor Criteria:
Fever (>38)
Immunological phenomena
- Roth spots
- splinter haemorrhages
- Olser’s nodes
- glomerulonephritis
- rheumatoid factor
Vascular phenomena
- septic embolis (splenic infarct/abscess)
- Janeway lesions
Echocardiogram minor criteria
Predisposing features
- valvular disease
- prosthetic valves
Microbiological evidence that does not meet major criteria.
How is infective endocarditis managed?
IV abx
4 weeks = native heart valves
6 weeks = prosthetic heart valves
If bacteria unknown (native valve):
- 1st line: amoxicillin (+/-gentamicin)
- Pen-allergy/MRSA: vancomycin (+/- gentamicin)
If bacteria unknown (prosthetic valve):
- vancomycin + rifampicin + gentamicin
Staph aureus (native valve)
- 1st line: flucloxacillin
- 2nd line: vancomycin + rifampicin
Staph aureus (prosthetic valve)
- 1st line: flucloxacillin + rifampicin + gentamicin
Strep viridans (both)
- 1st line: benzylpenicillin
- 2nd line: vancomycin + gentamicin
HACEK:
- 1st line: ceftriaxone
Surgery required:
Haemodynamic instability
Severe heart failure
Severe sepsis despite antibiotics/failed medical therapy
Valvular obstruction
Infected prosthetic valve
Persistent bacteraemia
Repeated emboli
Aortic root abscess
Complications of infected endocarditis (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
