Infective endocarditis

Question 1

What is the strongest risk factor for developing infective endocarditis?

Answer 1

A previous episode of endocarditis.

Affected patients include those with previously normal valves, rheumatic valve disease, prosthetic valves, congenital heart defects, intravenous drug users, and those with recent piercings.

Question 2

Which valve is most commonly affected in infective endocarditis?

Answer 2

The mitral valve.

Question 3

What is the most common cause of infective endocarditis?

Answer 3

Staphylococcus aureus.

Particularly common in acute presentations and intravenous drug users.

Question 4

What was historically the most common cause of infective endocarditis?

Answer 4

Streptococcus viridans.

This is no longer the case, except in developing countries.

Question 5

What are the two most notable viridans streptococci?

Answer 5

Streptococcus mitis and Streptococcus sanguinis.

They are commonly found in the mouth and dental plaque.

Question 6

What is a common cause of endocarditis in patients following prosthetic valve surgery?

Answer 6

Coagulase-negative Staphylococci such as Staphylococcus epidermidis.

Usually the result of perioperative contamination.

Question 7

What is Streptococcus bovis associated with?

Answer 7

Colorectal cancer.

The subtype Streptococcus gallolyticus is most linked with colorectal cancer.

Question 8

What are some culture negative causes of infective endocarditis?

Answer 8

Prior antibiotic therapy, Coxiella burnetii, Bartonella, Brucella, and HACEK organisms.

HACEK includes Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella.

Question 9

What is a non-infective cause of endocarditis?

Answer 9

Systemic lupus erythematosus (Libman-Sacks) and malignancy (marantic endocarditis).

Question 10

What are the criteria for diagnosing infective endocarditis?

Answer 10

Infective endocarditis is diagnosed if pathological criteria are positive, or if there are 2 major criteria, or 1 major and 3 minor criteria, or 5 minor criteria.

Question 11

What constitutes pathological criteria for infective endocarditis?

Answer 11

Positive histology or microbiology of pathological material obtained at autopsy or cardiac surgery (valve tissue, vegetations, embolic fragments or intracardiac abscess content).

Question 12

What are the major criteria for infective endocarditis?

Answer 12

1. Positive blood cultures showing typical organisms, or persistent bacteraemia, or positive serology for specific pathogens, or positive molecular assays.
2. Evidence of endocardial involvement via positive echocardiogram or new valvular regurgitation.

Question 13

What are examples of typical organisms in positive blood cultures?

Answer 13

Typical organisms include Streptococcus viridans and the HACEK group.

Question 14

What are the minor criteria for infective endocarditis?

Answer 14

1. Predisposing heart condition or intravenous drug use.
2. Microbiological evidence does not meet major criteria.
3. Fever > 38ºC.
4. Vascular phenomena: major emboli, splenomegaly, clubbing, splinter haemorrhages, Janeway lesions, petechiae or purpura.
5. Immunological phenomena: glomerulonephritis, Osler’s nodes, Roth spots.

Question 15

What are poor prognostic factors for infective endocarditis?

Answer 15

1. Staphylococcus aureus infection
2. Prosthetic valve (especially ‘early’, acquired during surgery)
3. Culture negative endocarditis
4. Low complement levels

Question 16

What is the mortality rate according to organism for staphylococci?

Answer 16

30%

Question 17

What is the mortality rate according to organism for bowel organisms?

Answer 17

15%

Question 18

What is the mortality rate according to organism for streptococci?

Answer 18

5%

Question 19

What is the suggested antibiotic therapy for initial blind therapy in native valve endocarditis?

Answer 19

Amoxicillin, consider adding low-dose gentamicin

Question 20

What is the suggested antibiotic therapy if the patient is penicillin allergic, has MRSA, or severe sepsis?

Answer 20

Vancomycin + low-dose gentamicin

Question 21

What is the suggested antibiotic therapy for prosthetic valve endocarditis?

Answer 21

Vancomycin + rifampicin + low-dose gentamicin

Question 22

What is the suggested antibiotic therapy for native valve endocarditis caused by staphylococci?

Answer 22

Flucloxacillin

Question 23

What is the suggested antibiotic therapy for native valve endocarditis caused by staphylococci if penicillin allergic or MRSA?

Answer 23

Vancomycin + rifampicin

Question 24

What is the suggested antibiotic therapy for prosthetic valve endocarditis caused by staphylococci?

Answer 24

Flucloxacillin + rifampicin + low-dose gentamicin

Question 25

What is the suggested antibiotic therapy for prosthetic valve endocarditis caused by staphylococci if penicillin allergic or MRSA?

Answer 25

Vancomycin + rifampicin + low-dose gentamicin

Question 26

What is the suggested antibiotic therapy for endocarditis caused by fully-sensitive streptococci (e.g. viridans)?

Answer 26

Benzylpenicillin

Question 27

What is the suggested antibiotic therapy for endocarditis caused by fully-sensitive streptococci if penicillin allergic?

Answer 27

Vancomycin + low-dose gentamicin

Question 28

What is the suggested antibiotic therapy for endocarditis caused by less sensitive streptococci?

Answer 28

Benzylpenicillin + low-dose gentamicin

Question 29

What is the suggested antibiotic therapy for endocarditis caused by less sensitive streptococci if penicillin allergic?

Answer 29

Vancomycin + low-dose gentamicin

Question 30

What are the indications for surgery in infective endocarditis?

Answer 30

1. Severe valvular incompetence
2. Aortic abscess (often indicated by a lengthening PR interval)
3. Infections resistant to antibiotics/fungal infections
4. Cardiac failure refractory to standard medical treatment
5. Recurrent emboli after antibiotic therapy

Question 31

What did the 2008 NICE guidelines change regarding antibiotic prophylaxis for infective endocarditis?

Answer 31

The guidelines radically changed the list of procedures for which antibiotic prophylaxis is recommended.

Question 32

Which procedures do not require antibiotic prophylaxis according to NICE?

Answer 32

Dental procedures, upper and lower gastrointestinal tract procedures, genitourinary tract procedures (including urological, gynaecological, obstetric procedures, and childbirth), and upper and lower respiratory tract procedures (including ear, nose and throat procedures and bronchoscopy).

Question 33

What should be done for episodes of infection in people at risk of infective endocarditis?

Answer 33

Any episodes of infection should be investigated and treated promptly to reduce the risk of endocarditis developing.

Question 34

What antibiotic should be given to a person at risk of infective endocarditis undergoing a procedure with suspected infection?

Answer 34

They should be given an antibiotic that covers organisms that cause infective endocarditis.

Question 35

How do the NICE guidelines differ from the American Heart Association/European Society of Cardiology guidelines?

Answer 35

NICE guidelines do not advocate antibiotic prophylaxis for high-risk patients undergoing dental procedures, while the American Heart Association/European Society of Cardiology guidelines still recommend it.