Endocarditis Flashcards
What is infective endocarditis?
Inflammation of the valves of heart, most commonly aortic and mitral valves.
The incidence is around 2-6 per 100000 person-years.
A fever + new murmur means endocarditis until proven otherwise.
Risk factors of endocarditis.
Skin breaches (dermatitis, IV drugs/lines, wounds)
Renal failure
Immunosuppression
DM
Causes of endocarditis.
Poor dental hygiene
IV drug use
Dental treatment
Intravascular cannulae
Cardiac surgery
GI infection
Prostethic heart valve
Bicuspid heart valve
Congenital
Organisms that can cause endocarditis (broad)
Bacteria
Fungi
Bacteria that are common in endocarditis.
Viridans streptococci
Staph aureus
Strep bovis
Staph epidermidis
Enterococci
HACEK bacteria
Chlamydia
Fungi causing endocarditis.
Candida
Aspergillus
Histoplasma
Do coronary stents predispose a risk of developing endocarditis?
No.
Only valves and patches.
Most common organism causing endocarditis in native-valve IE.
Viridans group of streptococci (50%)
Staph. aureus 20%
Commonest organism causing IV drug user endocarditis.
Staph aureus (50-60%)
Organisms causing infective endocarditis (IE) after implantation of prostethic valve within 60 days; i.e. “early IE”.
Staph epidermidis most common but also staph aureus.
Organisms causing IE > 60 days after implantation of a prosthetic valve; i.e. “late infection”.
Viridans streptococci
S. aureus
S. epidermidis
Presumed to have been acquired in the community via haematological spread.
Organisms associated with prolonged indwelling vascular catheter causing IE.
S. aureus
Rarely candida
Enterococcal endocarditis represent around 10% of all IE cases.
What is the underlying cause usually?
Disease of urinary or GI tract.
Around 2-10% of IE are caused by a fungi such as Candida or Aspergillus.
What is this usually associated with?
Immunosuppression
IV drug use
Cardiac surgery
Prolonged exposure to antimicrobial drugs
IV feeding
In around 5% of patients with proven IE have negative blood cultures.
Why might this be?
Because the patient might already be on antimicrobial drugs
or
Infection with slow-growing or fastidious organisms.
Give examples of slow-growing or fastidious organisms.
HACEK organisms
Nutrionally variant streptococci
Coxiella burnetii
Brucella spp.
What are the HACEK organisms?
Haemophilus
Actinobacillus
Cardiobacterium
Eikenella
Kingella
How does the mortality vary with organisms?
4-16% with viridans streptococci
25-47% with S. aureus
> 50% with fungal infections
Signs of IE.
Fever
Rigors
Night sweats
Malaise
Weight loss
Anaemia
Splenomegaly
Clubbing
Murmurs
Cardiac failure
Haematuria
Skin lesions in IE.
Splinter haemorrhages
Osler nodes
Janeway lesions
Petechiae
Investigations in IE.
Bloods - FBC, ESR and CRP, U&Es, LFTs
Urine dipstick and MSU
CXR
ECG
Blood cultures
Echocardiogram
How are the blood cultures performed in suspected IE?
Three sets of blood cultures at different times from differents sites at the peak of fever.
Some sources say the degree of fever does not matter, some say it does.
Should antibiotics be given before or after blood cultures?
If possible give after blood cultures.
Once antibiotics have been given it becomes much harder to identify a causative organism.
However if the patient is unstable you might not have time to do so.
What if cultures come back negative but there is high level of clinical suspicion of IE?
Samples can be taken in special media to allow growth of fastidious organisms.
This should be liaised with the duty microbiologist.
CXR findings in IE.
Cardiomegaly
Pulm. oedema
ECG findings in IE.
Might show prolonged PR interval or heart block if there is aortic root abscess.
Echocardiogram in IE.
Transthoracic will detect 65% of vegetations
Transoesophageal echo (TOE) will detect 95% of vegetations.
TOE is particularly useful for detection of mitral valve and prosthetic valve vegetations.
TOE is more sensitive at detecting aortic root and septal abscesses and leaflet perforations.
Diagnostic criteria of IE.
According to Modified Duke criteria for IE.
Explain modified Duke criteria.
2 major criteria
Or
One major criteria and three minor criteria
Or
All 5 minor criteria
Major criteria of modified Dukes.
Positive blood cultures;
Typical organism in 2 separate cultures or…
Peristently +ve blood cultures; 3 > 12h apart or…
Single +ve for Coxiella burnetii
Endocardium involvement;
+ve Echo for vegetations, abscess, pseudoaneurysm, dehiscence of prosthesis or…
Abnormal activity around prosthetic valve or…
Paravalvular lesions on cardiac CT
Minor criteria of modified Duke’s.
Predisposing factors;
Cardiac lesion, IV drug user, valvular abnormality
Fever > 38C
Vascular phenomena
Immunological/vasculitis phenomena
+ve blood culture that does not meet major criteria
Suggestive echo findings
Explain the basic of IE treatment.
A tunnelled central venous line can be very useful when prolonged courses of IV antibiotics are required, such as in IE treatment.
The antibiotics such always be discussed with the duty microbiologist.
Blind therapy when there is a native valve or prosthetic valve implanted over 1 year ago.
Ampicillin, flucloxacillin and gentamicin
If allergic to penicillin then give vancomycin + gentamicin.
If it is thought to be g -ve then given meropenem and vancomycin.
Blind therapy where there is a prosthetic valve.
Vancomycin + gentamicin + rifampicin
Treatment of streptococci IE (e.g. viridans)
Benzylpenicillin IV (vanco if allergic) + low dose gentamicin.
Treatment of enterococcal IE (e.g. Enterococcus faecalis)
Amoxicillin IV (or vanco if allergic) + low dose gentamicin.
Treatment of staphylococcal IE. (e.g. S. aureus, epidermidis)
Flucloxacillin (benzylpenicillin if penicillin sensitive, or vanco if penicillin allergic or MRSA) + gentamicin (or fusidic acid)
Indications of surgery in IE.
Heart failure
Valvular obstruction
Repeated emboli
Fungal IE (can also be given antifungals)
Peristent bacteraemia
Myocardial abscess
Unstable infected prosthetic valve
Valve dehiscence
Uncontrolled infection
Coxiella burnetii infection
Paravalvar infection
Sinus of Valsalve aneurysm
Monitoring of IE and response to therapy.
Echo once weekly to assess vegetation size and look for complications
ECG at least twice weekly to detect conduction disturbances, which may indicate development of an aortic root abscess in aortic valve infection.
Blood tests twice weekly - ESR, CRP, FBC and U&Es.
