Infective endocarditis Flashcards
(33 cards)
What is infective endocarditis?
-infection of the endothelium of the heart
What are four predisposing factors for infective endocarditis?
Heart valve abnormality:
- calcification/sclerosis in elderly
- congenital heart disease
- post rheumatic fever
Prosthetic heart valve
Intravenous drug users
Intravascular lines
What is the pathogenesis of infective endocarditis?
Heart valve damaged
Turbulent blood flow over roughened endothelium
Platelets / fibrin deposited
Bacteraemia (may be very transient) e.g. from dental treatment
organisms settle in fibrin/platelet thrombi becoming a microbial vegetation
Infected vegetations are friable and break off, becoming lodged in the next capillary bed they encounter causing abscesses or haemorrhage - may be fatal
Usually left side of heart affected (mitral and aortic valves) unless IDU and then it’s right sided
What organisms cause endocarditis in a native heart valve? (4)
Staphylococcus aureus (38%) - IVDU Viridans streptococci (31%) - mouth/dentist Enterococcus sp (8%) Staph epidermidis (6%) - indwelling lines/surgery
What are the unusual organisms that cause endocarditis?
Atypical organisms:
Bartonella, Coxiella burnetii (Q-fever), Chlamydia, Legionella, Mycoplasma, Brucella
Gram-negatives:
-HACEK organisms:
Haemophilus spp. , Aggregatibacter spp, ( was Actinobacillus) , Cardiobacterium, Eikenella sp., Kingella sp.
-Non HACEK gram negatives
Fungi - in immunocompromised individuals/IVDU/IV lines
What two signs = endocarditis until proven otherwise?
New murmur + fever
describe the clinical features of an acute endocarditis? 10
- fever
- new heart murmur
- haematuria (secondary to renal failure)
- rigors
- night sweats
- splinter haemorrhages
- nail fold infarcts
- roth spots
- embolic incidents (TIA/Stroke 15%)
- malaise
Overwhelming sepsis and cardiac failure usually due to staph aureus
In subacute endocarditis what are the clinical features? 8
- fever
- rigors
- murmurs
- palpable spleen (coxiella infection causes large liver/spleen)
- clubbing
- general fatigue
- purpura
- oslers nodes
- janeway lesions (specific for endocarditis)
(viridans)
How is infective endocarditis diagnosed?
For definitive information on making a diagnosis, we have the Duke criteria. This divides symptoms into two categories; major and minor criteria
You can then assess whether IE is present or not.
IE definitely present: 2 major criteria present OR 1 major criteria, 3 minor criteria OR 5 minor criteria
IE possibly present:
1-4 minor criteria
AND
No other more likely diagnosis
What are dukes major criteria?
Positive blood culture for infective organisms (on 2 separate tests if >12 hours apart, or on 3/3 or 3/4 tests >1 hour apart)
-if blood culture is negative consider serology for atypicals
Evidence of IR from other tests:
- Echocardiogram shows strictures, unusual blood flow, implanted /unusual material
- Abscesses
New valve regurgitation
What are dukes minor criteria? 6
Fever >38’C
Predisposition to IE; e.g. IV drug user, congenital heart condition, prosthetic valve
Unusual echo, but not with findings stated above
Immunological factors present; Roth spots, Osler’s nodes, glomerulonephritis, rheumatoid factor
Blood cultures positive, but major criteria not satisfied
Vascular abnormalities; embolism, aneurysm, infarcts, conjunctival haemorrhage, intracranial haemorrhage etc
Describe the differences between transthoracic echocardiography and transoesophageal echocardiography?
TTE: rapid, non-invasive. high specificity but sensitivity only 60-70%. vegetations below 2mm easily missed.
TOE: echo via oesophagus. higher sensitivity 90%. identifies vegetations of 1mm and higher. better view of prosthetic heart valves
When is a TTE used in the diagnosis of infective endocarditis?
in everyone with native heart valves where there’s a clinical suspicion of IE
When is a TOE used in the diagnosis of infective endocarditis?
In those with a prosthetic heart valve
In those with a positive or non-diagnosis TTE
In those with a negative TTE but clinical suspicion is still high
How should blood cultures be taken when infective endocarditis is suspected?
3 sets of optimally filled blood cultures should be taken from peripheral sites
(does not require to be
different sites )
with ≥ 6 hours between them prior to commencing anti microbial therapy
severe sepsis or septic shock
at the time of presentation, 2 sets of optimally filled blood cultures should be taken at different times within 1 hour prior to commencement of empirical therapy,
Other than blood cultures what other general lab tests are important when suspecting infective endocarditis?
Full blood count- A normocytic, normochromic anaemia (anaemia of chronic disease) may be present, as are polymorphonuclear leucocytes.
Thrombocytopaenia (low platelet count) and thrombocytosis (high platelet count) are also common.
U+E- Renal dysfunction is common
LFT’s- ALP is likely to be raised, other values may be slightly abnormal
Inflammatory markers – CRP and ESR are likely to be raised. CRP is a more acute phase protein than ESR, and thus is more accurate and useful in monitoring progress.
Urine – proteinurea may occur, and microscopic haematuria is nearly always present
What is the difference between the pathophysiology of infection in early (within 60days) and late presentations of prosthetic valve endocarditis?
Early- usually infected at time of valve insertion and usually due to Staphylococcus epidermidis or Staphylococcus aureus
Late - up to many years after valve insertion - due to co-incidental bacteraemia. Wide range of possible organisms
What is the empirical treatment for infective endocarditis
- native heart valve
- prostetic heart valve
- IVDU ?
Native = IV amoxicillin and gentamicin
(if penicillin allergic vancomycin and gentamicin)
Prosthetic valve endocarditis
Vancomycin & gentamicin IV
Add in day 3 to 5 (delayed) rifampicin PO
often valve replacement is required
Drug user endocarditis
Flucloxacillin IV
After that as guided by culture results
What is the treatment for
- S.Aureus (not-MRSA)
- MRSA
- strep. Viridans
- enterococcus
- s. epidermidis
Staphylococcus aureus (not MSSA) Flucloxacillin IV
MRSA treat as per prosthetic valve
Viridans streptococci
Benzylpenicillin iv & gentamicin iv (synergistic)
Enterococcus sp.
Amoxicillin/ vancomycin & gentamicin IV
Staphylococcus epidermidis
Vancomycin & gentamicin IV & rifampicin PO
Describe the algorithm in identifying the organism for infective endocarditis?
If blood cultures are positive can do antimicrobial susceptability testing
if blood cultures are negative can do serologies and PCR, if then PCR is negative check anti-nuclear antibodies, anti-phospholipid antibodies and anti-pork antibodies
What specific treatment is given for:
- S. aureus
- MRSA
- Viridans streptococci
- Enterococcus sp
- staphylococcus epidermidis?
Staphylococcus aureus (not MSSA) Flucloxacillin IV
MRSA treat as per prosthetic valve
Viridans streptococci
Benzylpenicillin iv; gentamicin iv (synergistic)
Enterococcus sp.
Amoxicillin/ vancomycin; gentamicin IV
Staphylococcus epidermidis
Vancomycin IV , gentamicin IV, rifampicin PO
in infective endocarditis:
How long is IV abiotics given for? what is important to monitor? what to do if failing on abiotics?
IV antibiotics usually given for 4 - 6 weeks
Monitor cardiac function, temperature and serum C-reactive protein (CRP)
If failing on antibiotic therapy, consider referral for surgery early
what does OPAT mean in the management of infective endocarditis?
out patient abiotic therapy
When is OPAT considered in the management of infective endocarditis?
Critical phase wks 0-2:
- if oral strep. or strep bovis
- AND if native valve/pt stable
Continuation phase wks 2+:
- if medically stable
- NOT if HF, echo is concern, neuro signs, renal impairment
