Infective Endocarditis

Question 1

RFs of IE?

Answer 1

Congenital heart defects e.g. VSDs, PDA, stenosis
Valve replacements
Dental work
Catheters, prostheses etc
IVDU
Autoimmune disorders
Hx of IE 
Rheumatic heart disease
Haemodialysis, colonoscopy, ERCP

Question 2

What is rheumatic heart disease?

Answer 2

Autoimmune attack on strep pyogenes infection

Question 3

Describe the immune response to IE

Answer 3

Valves have poor blood supply so WBCs can’t attack -> poor cell mediated immunity
Microemboli go to spleen where humoral arm (reticuloendothelial system) takes over, forming AgAb complexes

Question 4

Is a substantial neutrophilia common in IE? What may it suggest?

Answer 4

No. If very high may suggest abscess formation

Question 5

What cells are responsible for the front line fighting of IE infection?

Answer 5

Thrombocytes

Question 6

What is the non-infected prerequisite to IE and what is this caused by?

Answer 6

Nonbacterial thrombotic endocarditis

Caused by sterile fibrin-platelet vegetation on endocardium

Question 7

What is the most common causative agent of IE?

Answer 7

Strep viridans - a haemolytic

Question 8

2 other most common causative agents of IE (besides strep viridans)?

Answer 8

Staph aureus

Coagulase negative staphylococci

Question 9

Which bacterial pathogen is often commensal in the dental cavity and implicated in NVE/late PVE?

Answer 9

Strep viridans

Question 10

Which bacterial pathogen is more associated with subacute, community acquired IE?

Answer 10

Strep viridans

Question 11

What bacterial pathogen is associated with acute, severe healthcare-associated IE?

Answer 11

Staph aureus

Question 12

What bacterial is most likely to be causative in acute IVDU-associated IE?

Answer 12

Staph aureus

Question 13

Which bacteria is most implicated in PVE?

Answer 13

Coagulase-negative staphylococci

Question 14

What are some culture-negative IE pathogens?

Answer 14

Fungi - aspergillus, candida
Coxiella
HACEK

Question 15

Anaerobes associated with IE particularly post GI surgery?

Answer 15

Enterococci

Question 16

What causes arthralgia associated with IE?

Answer 16

Deposition of AbAg complexes in joints

Question 17

Features of IE associated with acute presentation?

Answer 17

Fever, rigors
Cardiac - conduction abnormalities, acute heart failure
Septic shock

Question 18

Features associated with subacute IE?

Answer 18

Intermittent PUO, weight loss, lethargy, arthralgia

Question 19

What would a spiking fever with new conduction abnormalities on ECG suggest?

Answer 19

Aortic root abscess secondary to IE

Question 20

4 areas of clinical signs of IE?

Answer 20

Systemic
Cardiac
Embolic
Immune vasculitis

Question 21

Systemic signs of IE?

Answer 21

Petechial haemorrhage - conjunctiva, mucosa (palate, buccal)
Splinter haemorrhage
Roth spots
Janeway lesions
Oslers nodes
Clubbing

Question 22

Cardiac signs of IE?

Answer 22

New or changing murmur
Conduction abnormalities
Heart failure

Question 23

Embolic phenomena associated with IE?

Answer 23

Pulmonary embolism (R), abscess etc
Stroke, MI, DVT...

Question 24

Immune vasculitis features of IE?

Answer 24

Immune complex nephritis - haematuria and microalbuminuria
Splenomegaly
Arthritis etc

Question 25

Blood culture requirements for IE?

Answer 25

At least 3 from any site, if poss when spiking fever

Question 26

Best Echo modality for investigating IE?

Answer 26

Transoesophageal

Question 27

What are the general principles of antimicrobial therapy for IE?

Answer 27

Long term (4-6weeks) high conc synergistic therapy

Question 28

What empirical treatment is recommended for severe IE of unknown origin?

Answer 28

Vancomycin + Gentamycin (covers MRSA)

Question 29

Rx for IE confirmed to be of strep viridans or enterococcus origin?

Answer 29

Amoxicillin + Gentamycin

Question 30

What surgical option needs to be taken for PVE?

Answer 30

Clear vegetation as much as possible then surgically replace as biofilms are resistant to eradication