Infective Endocarditis

Question 1

What is the strongest risk factor for developing infective endocarditis?

Answer 1

A previous episode of endocarditis.

Question 2

What types of patients are affected by infective endocarditis?

Answer 2

Patients with previously normal valves, rheumatic valve disease, prosthetic valves, congenital heart defects, intravenous drug users (IVDUs), and those with recent piercings.

Question 3

Which valve is most commonly affected in infective endocarditis?

Answer 3

The mitral valve.

Question 4

What is the most common cause of infective endocarditis?

Answer 4

Staphylococcus aureus.

Question 5

In which patient group is Staphylococcus aureus particularly common?

Answer 5

In acute presentations and intravenous drug users (IVDUs).

Question 6

What was historically the most common cause of infective endocarditis?

Answer 6

Streptococcus viridans.

Question 7

What are the two most notable viridans streptococci?

Answer 7

Streptococcus mitis and Streptococcus sanguinis.

Question 8

What is the link between viridans streptococci and infective endocarditis?

Answer 8

Endocarditis caused by these organisms is linked with poor dental hygiene or following a dental procedure.

Question 9

What is the role of coagulase-negative Staphylococci in infective endocarditis?

Answer 9

They commonly colonize indwelling lines and are the most common cause of endocarditis in patients following prosthetic valve surgery.

Question 10

What happens to the spectrum of organisms causing endocarditis after 2 months?

Answer 10

It returns to normal, with Staphylococcus aureus being the most common cause.

Question 11

What is Streptococcus bovis associated with?

Answer 11

Colorectal cancer.

Question 12

Which subtype of Streptococcus bovis is most linked with colorectal cancer?

Answer 12

Streptococcus gallolyticus.

Question 13

What are some non-infective causes of endocarditis?

Answer 13

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

Question 14

What are some culture negative causes of infective endocarditis?

Answer 14

Prior antibiotic therapy, Coxiella burnetii, Bartonella, Brucella, and HACEK organisms (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella).

Question 15

What are the criteria for diagnosing infective endocarditis?

Answer 15

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 16

What constitutes pathological criteria for infective endocarditis?

Answer 16

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

Question 17

What are the major criteria for infective endocarditis?

Answer 17

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

Question 18

What are the specific blood culture conditions for major criteria?

Answer 18

Two positive blood cultures showing typical organisms (e.g., Streptococcus viridans, HACEK group), or persistent bacteraemia from two cultures taken > 12 hours apart, or three or more positive blood cultures with less specific pathogens (e.g., Staph aureus, Staph epidermidis).

Question 19

What are the minor criteria for infective endocarditis?

Answer 19

1. Predisposing heart condition or intravenous drug use.
2. Microbiological evidence that 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).