Micro: Endocarditis

Question 1

Most common cause of damaged heart valves.

Answer 1

Calcific aortic stenosis (commonly seen in elderly)

Question 2

What are the 4 steps in the progression to endocarditis?

Answer 2

1. Valve surface altered
2. Deposition of platelets and fibrin (Non-Bacterial Thrombotic Endocarditis or NBTE)
3. Bacteria start to bind to the NBTE
4. More bacteria and more fibrin build up

Question 3

3 most common organisms that lead to acute Native Valve Endocarditis (NVE).

Answer 3

1. Staph aureus: abscess or puss lesion
2. Strep penumo: from pneumonia
3. Strep pyogenes: from rheumatic fever

Question 4

Two most common organisms (or groups) that lead to Subacute NVE.

Answer 4

1. Viridans strep: mainly strep mutans from dental caries
2. HACEK:
   Haemophilus parainfluenzae, Aggregatibacter a., Cardiobacterium hominus, Eikenella, Kingella

Question 5

Most common cause of early Prosthetic Valve Endocarditis (PVE).

Answer 5

Less than 60 days after operation.
CoNS (S. saprophyticus and S. epidermidis)

-if the presentation occurs acutely it may be Staph aureus due to infection during the procedure

Question 6

Most common cause of late PVE.

Answer 6

Strep sp.

Question 7

Most common cause of endocarditis in IVDU.

Answer 7

Staph aureus

Question 8

Virulence factor of oral Strep. (mutans, bovis, etc.)

Answer 8

Dextran production: retards antimicrobial therapy

Question 9

Virulence factor of Enterococci and Viridans strep.

Answer 9

FimA

-adhesion protein that binds platelet-fibrin matrices

Question 10

Virulence factor of S. aureus that causes endocarditis.

Answer 10

Adhesion proteins that bind vonWillebrand factor receptors of clots

Question 11

Who are the Abiotrophia sp. and what is the most common complication of endocarditis caused by this family?

Answer 11

Strep family (formerly Nutritionally Variant Strep)

• require L-cysteine or B6
• prone to systemic embolizations

Question 12

Bacteria that are PYR(+)

Answer 12

Group D strep (GI normal flora)

Strep pyogenes

Question 13

Causative agent in a patient that develops endocarditis while also suffering from colon cancer.

Answer 13

Strep bovis

Question 14

Major complication of Subacute endocarditis caused by HACEK.

Answer 14

Frequent vegetations that can embolize

Question 15

Main cause of Subacute Endocarditis caused during periodontal disease causing a fever.

Answer 15

Aggregatibacter actinomycetemcomitans

Question 16

Main cause of Subacute Endocarditis caused during periodontal disease without a fever.

Answer 16

Cardiobacterium hominus

Question 17

Cause of Subacute Endocarditis caused by human bite

also in IV drug abusers and dental work

Answer 17

Eikenella corrodens

-smells like bleach

Question 18

Cause of Subacute Endocarditis seen in children.

Answer 18

Kingella kingae

Question 19

What are the 2 major Duke criteria?

Answer 19

1. Positive Blood Culture

2. Evidence of Endocardial Involvement

Question 20

What is the procedure for fulfilling the positive blood culture criteria?

Answer 20

Acute: positive culture in 3 or 3/4 cultures done 15-20 minutes apart

Subacute: 2 positive cultures drawn at least 12 hrs. apart

Question 21

What is the procedure for fulfilling the positive endocardial involvement criteria?

Answer 21

1. Positive Echocardiogram (TEE or TTE)

2. Auscultation (hearing a new murmur and change form an old murmur indicating new regurgitation)

Question 22

What are the 6 minor criteria for Duke?

Answer 22

1. Predisposition (IVDU or heart disease)
2. Fever
3. Vascular phenomena (emboli, Janeway lesions)
4. Immunologic Phenomena (Roth Spots, oslers nodes)
5. Micro evidence (positive blood culture that doesn’t meet major)
6. Echocardio findings (that don’t meet major)

Question 23

How is the Duke criteria used?

Answer 23

Definite IE:

1. 2 major
2. 1 major + 3 minor
3. 5 minor

Possible IE

1. 1 major + 1 minor
2. 3 minor