CARDIO: Infective Endocarditis

Question 1

Diagnostic investigations for infective endocarditis?

Answer 1

Blood cultures (3 different sites over several hours)
Transoesophageal Echocardiogram 

Question 2

What are some cardiac RF for developing Infective endocarditis?

Answer 2

Mitral valve prolapse
Prosthetic (valves + patches NOT stents)
bicuspid aortic valve disease
rheumatic heart disease
congenital heart disease

Question 3

How are normal heart valves often involved in infective endocardiits?

Answer 3

previously normal heart valves can be infected due to a intravascular device e.g. central line?

Question 4

What are the most common organisms involved in native-valve Infective Endocarditis?

Answer 4

Staph aurues is now the most common!

Strep viridans (50%)
Staph aureus (20%)

Question 5

What is the most common organism for Infective Endocarditis in IV drug users?

Answer 5

Staph aureus (50-60%) of cases

Question 6

What is the organism most commonly involved in ‘early’ (up to 1 year) Infective Endocarditis, post prosthetic heat valve operation?

Answer 6

Peri-operative contamination- mainly staphylococci

especially coagulase - negative e.g. staph epidermis

Question 7

What is the organism most commonly involved in ‘late’ Infective Endocarditis, post prosthetic heat valve operation?

Answer 7

Viridans streptococci

Staph aureus

coagulase negatvie staph e.g. staph epidermis

Question 8

In Infective Endocarditis, what organisms might suggest concurrent disease of GU / GI tract?

Answer 8

Enterococcal infective carditis 10% of all cases

e.g. Enterococcus feacalis

Question 9

Which groups of people at risk of contracting Infective Endocarditis due to Fungi (+ which types) ?

Answer 9

E.g. Candidas / Aspergillus sp.

Immunosuppression
IV drug use 
cardiac surgery 
prolonged exposure to AB
IV feeding

Question 10

Why might blood cultures be negative in cases of infective endocarditis?

Answer 10

5% of those with IE is negative

often due to recent exposure to AB

or

Infection with slow growing / fastidious organisms e.g. streptococci, Coxiella Burnetii or Brucella

Question 11

What is the main causes of mortality in Infective Endocarditis?

Answer 11

Heart failure
CNS emboli
uncontrolled infection

Question 12

What features should make you immediately suspect Infective Endocarditis in a pt?

Answer 12

Unexplained fever
Bacteraemia
systemic illness
and / or new murmur

Question 13

What initial investigations should be performed on a pt with suspected Infective Endocarditis you have just admitted to hospital?

Answer 13

Bloods:
FBC
ESR / CRP
U&E
LTF
urine dip analysis and MSU for microscopy / culutre.
BLOOD CULTURES - 3 SETS FROM 3 DIFFERENT SITES **

Imaging:
CXR
ECG
ECHOCARDIOGRAM - TRANS OESOPHAGEAL ECHOCARDIOGRAM **

Question 14

How many blood cultures, over how long and where should you take in a pt with Infective Endocarditis?

Answer 14

at least 3 (ideally 6) from different sites over several hours.

Sampling during temperature peak does not make cultures more sensitive

Question 15

In a pt who is STABLE and has Infective Endocarditis, is it reasonable to delay AB treatment to take blood cultures - TRUE / FALSE

Answer 15

TRUE

once AB have been given harder to identify a causative organism

Question 16

What imaging modality should you use to visualise Infective Endocarditis?

Answer 16

Echocardiogram

Transthoracic echo - 65% of vegetations

Transoesophageal echo (TOE) - 95% of vegetations

Question 17

Which type of echocardiography is better for detecting mitral valve and prosthetic valve vegetations?

Answer 17

Transoesophageal echocardiography (TOE)

Also better at detecting aortic root, septal abscesses and leaflet perforations

Question 18

Diagnostic criteria for Infective Endocarditis: How many of major / minor criteria do you need to make a diagnosis?

Answer 18

2 major

or

1 major + 3 minor

or

5 minor

Question 19

What are the major criteria for diagnosing Infective Endocarditis?

Answer 19

1. +ve blood cultures
   - typical org from 2 BC
   - +ve BCs >12 hrs apart
   - >3 +ve BCs >1hour
2. Endocardial involvement
3. +ve echo findings (abscess / vegetations)
4. New valvular regurgitation
5. dehiscence of prosthesis

Question 20

What are the minor criteria for diagnosing Infective Endocarditis?

Answer 20

1. Predisposing valvular or cardiac abnormality
2. IV drug user
3. Pyrexia > 38°C
4. Embolic phenomenon
5. Vasculitic phenomenon
6. Blood cultures suggestive (grown but not achieving major criteria)
7. Suggestive echo findings (but not meeting major criteria)

Question 21

In terms of the management of Infective Endocarditis, what is the general principal? (before organism specific)

Answer 21

AB therapy

tunnelled central venous line good for prolonged IV AB (discuss regimens with duty microbiologist)

Question 22

What AB therapy is recommended for Infective Endocarditis caused by Viridans streptococci?

Answer 22

IV Benzylpenicillin

(+ low dose IV gentamicin 80 mg BD)

(Vancomycin if penicillin allergic)

Question 23

What AB therapy is recommended for Infective Endocarditis caused by Enterococci e.g. Enterococcus faecalis?

Answer 23

IV amoxicillin

(+ low dose IV gentamicin 80 mg BD)

(Vancomycin if penicillin allergic)

Question 24

What AB therapy is recommended for Infective Endocarditis caused by staphylocci, e.g. Staph aureus / Staph epidermis?

Answer 24

Flucloxacillin

Vancomycin if penicillin allergic

plus gentamicin / fusidic acid

Question 25

How would you recommend response to AB therapy in a pt with Infective Endocarditis? imaging, bloods etc

Answer 25

1. bedside reviews of clinical status
2. Echo 1 x weekly
   (vegetation size, complications e.g. abscess / valve destruction)
3. ECG 2 x weekly
   conduction disturbances- aortic root abscess / valve infection
4. Blood tests 2 x weekly
   ESR / CRP/ FBC / U&Es

AB - 6 weeks depending on response

Question 26

Referral for surgery is indicated for pts with Infective Endocarditis who have …..

Answer 26

• Cardiac failure (valve compromise)
• Valve dehiscence
• Uncontrolled infection despite AB
• Fungal / Coxiella burnetii infection
• Relapse after medical therapy
• Threatened / actual systemic embolism
• Para-valvular infection (aortic root abscess)
• Valve obstruction

Common exam question: PR interval prolongation in a patient with Infective Endocarditis is an indication for surgery as it can be secondary to aortic root abscess

Question 27

Diagnostic investigations for infective endocarditis?

Answer 27

Blood cultures (3 different sites over several hours)
Echocardiogram (transoesophageal)