Endocarditis

Question 1

What is infective endocarditis?

Answer 1

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.

Question 2

Risk factors of endocarditis.

Answer 2

Skin breaches (dermatitis, IV drugs/lines, wounds)

Renal failure

Immunosuppression

DM

Question 3

Causes of endocarditis.

Answer 3

Poor dental hygiene

IV drug use

Dental treatment

Intravascular cannulae

Cardiac surgery

GI infection

Prostethic heart valve

Bicuspid heart valve

Congenital

Question 4

Organisms that can cause endocarditis (broad)

Answer 4

Bacteria

Fungi

Question 5

Bacteria that are common in endocarditis.

Answer 5

Viridans streptococci

Staph aureus

Strep bovis

Staph epidermidis

Enterococci

HACEK bacteria

Chlamydia

Question 6

Fungi causing endocarditis.

Answer 6

Candida

Aspergillus

Histoplasma

Question 7

Do coronary stents predispose a risk of developing endocarditis?

Answer 7

No.

Only valves and patches.

Question 8

Most common organism causing endocarditis in native-valve IE.

Answer 8

Viridans group of streptococci (50%)

Staph. aureus 20%

Question 9

Commonest organism causing IV drug user endocarditis.

Answer 9

Staph aureus (50-60%)

Question 10

Organisms causing infective endocarditis (IE) after implantation of prostethic valve within 60 days; i.e. “early IE”.

Answer 10

Staph epidermidis most common but also staph aureus.

Question 11

Organisms causing IE > 60 days after implantation of a prosthetic valve; i.e. “late infection”.

Answer 11

Viridans streptococci

S. aureus

S. epidermidis

Presumed to have been acquired in the community via haematological spread.

Question 12

Organisms associated with prolonged indwelling vascular catheter causing IE.

Answer 12

S. aureus

Rarely candida

Question 13

Enterococcal endocarditis represent around 10% of all IE cases.

What is the underlying cause usually?

Answer 13

Disease of urinary or GI tract.

Question 14

Around 2-10% of IE are caused by a fungi such as Candida or Aspergillus.

What is this usually associated with?

Answer 14

Immunosuppression

IV drug use

Cardiac surgery

Prolonged exposure to antimicrobial drugs

IV feeding

Question 15

In around 5% of patients with proven IE have negative blood cultures.

Why might this be?

Answer 15

Because the patient might already be on antimicrobial drugs

or

Infection with slow-growing or fastidious organisms.

Question 16

Give examples of slow-growing or fastidious organisms.

Answer 16

HACEK organisms

Nutrionally variant streptococci

Coxiella burnetii

Brucella spp.

Question 17

What are the HACEK organisms?

Answer 17

Haemophilus

Actinobacillus

Cardiobacterium

Eikenella

Kingella

Question 18

How does the mortality vary with organisms?

Answer 18

4-16% with viridans streptococci

25-47% with S. aureus

> 50% with fungal infections

Question 19

Signs of IE.

Answer 19

Fever

Rigors

Night sweats

Malaise

Weight loss

Anaemia

Splenomegaly

Clubbing

Murmurs

Cardiac failure

Haematuria

Question 20

Skin lesions in IE.

Answer 20

Splinter haemorrhages

Osler nodes

Janeway lesions

Petechiae

Question 21

Investigations in IE.

Answer 21

Bloods - FBC, ESR and CRP, U&Es, LFTs

Urine dipstick and MSU

CXR

ECG

Blood cultures

Echocardiogram

Question 22

How are the blood cultures performed in suspected IE?

Answer 22

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.

Question 23

Should antibiotics be given before or after blood cultures?

Answer 23

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.

Question 24

What if cultures come back negative but there is high level of clinical suspicion of IE?

Answer 24

Samples can be taken in special media to allow growth of fastidious organisms.

This should be liaised with the duty microbiologist.

Question 25

CXR findings in IE.

Answer 25

Cardiomegaly

Pulm. oedema

Question 26

ECG findings in IE.

Answer 26

Might show prolonged PR interval or heart block if there is aortic root abscess.

Question 27

Echocardiogram in IE.

Answer 27

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.

Question 28

Diagnostic criteria of IE.

Answer 28

According to Modified Duke criteria for IE.

Question 29

Explain modified Duke criteria.

Answer 29

2 major criteria

Or

One major criteria and three minor criteria

Or

All 5 minor criteria

Question 30

Major criteria of modified Dukes.

Answer 30

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

Question 31

Minor criteria of modified Duke’s.

Answer 31

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

Question 32

Explain the basic of IE treatment.

Answer 32

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.

Question 33

Blind therapy when there is a native valve or prosthetic valve implanted over 1 year ago.

Answer 33

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.

Question 34

Blind therapy where there is a prosthetic valve.

Answer 34

Vancomycin + gentamicin + rifampicin

Question 35

Treatment of streptococci IE (e.g. viridans)

Answer 35

Benzylpenicillin IV (vanco if allergic) + low dose gentamicin.

Question 36

Treatment of enterococcal IE (e.g. Enterococcus faecalis)

Answer 36

Amoxicillin IV (or vanco if allergic) + low dose gentamicin.

Question 37

Treatment of staphylococcal IE. (e.g. S. aureus, epidermidis)

Answer 37

Flucloxacillin (benzylpenicillin if penicillin sensitive, or vanco if penicillin allergic or MRSA) + gentamicin (or fusidic acid)

Question 38

Indications of surgery in IE.

Answer 38

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

Question 39

Monitoring of IE and response to therapy.

Answer 39

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.