Infective Endocarditis Flashcards
Bacteraemia
Presence of bacteria in the bloodstream
Skin organisms associated with cardiac implantable electronic devices
Staphylococcus aureus, staphylococcus epidermis, corynebacterium sp., propionibacterium acnes
Risk factors for infection after cardiac implantable electronic devices
- Pre procedure prophylaxis
- Complexity of procedure
- Temporary pacer use
- Type of device
- Number of revisions/reinterventions
- Fever within 24 hours
- Heart failure, renal failure
- Haematoma post procedure
Implantable cardiac electronic devices:
- Generator pocket infection
Localised cellulitis, pain, swelling, discharge, wound breakdown
Non-specific signs and symptoms of systemic infection
Fevers, chills, night sweats, malaise, anorexia
When should blood cultures be taken?
Prior to starting antimicrobial therapy for cardiac infections, on clinical suspicion on implantable cardiac electronic devices infection with chronic or subacute presentation
Blood cultures:
- How many taken?
- How far apart?
- 3 sets from peripheral sites
- >6 hours between them
Infective endocarditis
Infection of the endothelium of the heart valves
Predisposing factors for infective endocarditis
Heart valve abnormality (calcification/sclerosis in elderly, congenital heart disease, post rheumatic fever), prosthetic heart valve, PWID, IV lines, previous dental treatment
Pathogenesis of infective endocarditis
- Heart valve damaged
- Turbulent blood flow over roughened endothelium
- Platelets/fibrin deposited
- Bacteraemia
- Organisms settle in fibrin/platelet thrombi becoming a microbial vegetation
- Infected vegetations are friable (susceptible to break off) and break off, becoming lodged in the next capillary bed they encounter causing abscesses or haemorrhage
What side of the heart is usually affected by endocarditis
Left side
Usual organisms causing infective endocarditis
Staph aureus, viridian’s group streptococci, enterococcus sp. (elderly), staph epidermis (think metal or plastic)
Unusual organisms causing infective endocarditis
Atypical organisms, gram negatives, fungi
Atypical organisms causing infective endocarditis
Bartonella, coxiella burnetii (Q fever), chlamydia, legionella, mycoplasma
Gram negative organisms causing infective endocarditis
HACEK organisms
HACEK organisms
H = haemophilia spp. A = aggregatibacter spp. C = cardiobacterium E = eikenella sp. K = kingella sp.
What test do you do instead of blood culture for unusual organisms causing infective endocarditis?
Antibody test
Duke criteria
2 separate positive blood cultures with microorganism(s) typical for infective endocarditis
Echocardiographic evidence of endocardial involvement
New valvular regurgitation
Blood cultures for infective endocarditis
- Detection of endocarditis-specific pathogens in 2 blood cultures
Or - Microorganisms compatible with an IE in persistently positive blood cultures: at least 2 positive blood cultures from blood withdrawals at least 12 hours apart
Or
-A single positive blood culture with Coxiella burnetiid or a phase I IgG antibody titre >1:800
Subacute symptoms of infective endocarditis
Fever, malaise, weight loss, tiredness, breathlessness
Subacute signs of infective endocarditis
Fever, new or changing heart murmur, finger clubbing, splinter haemorrhages, splenomegaly, Roth spots, janeway lesions, Osler nodes, microscopic haematuria
First investigation for infective endocarditis
Transthoracic echo, then transoesophageal
Prosthetic valve endocarditis - early and late
Early - within 60 days, usually infected at time of valve insertion and usually due to staph epidermis or staph aureus
Late - up to many years later after valve insertion – due to co-incidental bacteraemia. Wide range of possible organisms
Endocarditis in PWID:
- What side is usually affected?
- Which organism is usually responsible?
- Right side (tricuspid valve)
- Staph aureus
