3.3.2. Infectious Endocarditis

Question 1

Define transient bacteremia.

Answer 1

Bacteria introduced into the bloodstream and readily cleared without evoking a detectable inflammatory response [gums]

Question 2

Define intermittent bacteremia.

Answer 2

Spread of infection from some extravascular site (kidney, lung, wounds) results in fever, inflammatory response

Question 3

Define continuous bacteremia

Answer 3

Seeded into the bloodstream from site of infection without circulatory system (endocarditis, vasculitis, infected catheter site); sometimes defined as three positive blood cultures within one day

Question 4

What are symptoms of endocarditis?

Answer 4

Fatigue, weakness, fever, night sweats, anorexia, heart murmur, and shortness of breath (SoB)

Question 5

Why are heart valves more susceptible to endocarditis?

Answer 5

They do not receive any blood and the white blood cells cannot enter, so there is no defensive mechanism at this site

Question 6

List the three steps for collecting a blood culture.

Answer 6

1. Decontaminate the skin with iodine based antiseptic, and palpate vein with sterile gloved finger
2. Collect adequate volume for 1:10 dilution in broth culture medium
3. Decontaminate bottle tops and transfer sample to broth

Question 7

What organism is responsible for acute endocarditis?

Answer 7

S. aureus

Question 8

What organism is responsible for subacute endocarditis?

Answer 8

viridans streptococci; S. sanguinis makes dextrans, which bind fibrin platelet aggregates on damaged heart valves

Question 9

Where is acute endocarditis found? How does it affect the valve?

Answer 9

The tricuspid valve. It destroys the valve.

Question 10

What are symptoms of subacute endocarditis?

Answer 10

Fevers, chills
Heart murmur
Symptoms of stroke
Clinical signs of embolic infection (“breakaway” infection that travels as an embolism)
CHF

Question 11

What are symptoms of subacute endocarditis?

Answer 11

More subtle presentation
Fatigue, malaise
Fever
Night sweats
Cough
Symptoms of CHF
Renal disease

Question 12

Name some gross physical characteristics that you would see on someone with endocarditis (acute and subacute).

Answer 12

1. Splinter hemorrhages (result of septic emboli (vegetation breaks off from valve))
2. Conjunctival petechiae
3. Osler’s nodes (result of septic emboli (vegetation breaks off from valve))
4. Janeway’s lesions (result of septic emboli (vegetation breaks off from valve)
   - small, painless, erythematous lesions on palm or sole
5. Fever
6. Roth spots (Round white spots on retina surrounded by hemorrhage)
7. Murmur
8. Emboli
9. Anemia

Question 13

What are some predisposing conditions for intravascular infection?

Answer 13

Most often will enter through the mouth or indwelling vascular device:

1. IV drug use
2. Mitral valve prolapse
3. Poor hygiene
4. Prosthetic heart valves (due to surgery)
5. Hemodialysis
6. Diabetes
7. Rheumatic heart disease

Question 14

What are HACEK organisms?

Answer 14

HACEK organisms - endocarditis with negative blood cultures- seronegative (they are hard to grow organisms)
Haemophilus
Actinobacillus
Cardiobacterium
Eikenella
Kingella

Question 15

What are measures for at risk individuals and the challenges in treatment of existing infections?

Answer 15

Maintain good hygiene
Treatment:
1. Determine antimicrobial susceptibility of agent
2. Select drug (or combination)
3. Administer IV antibiotics for 4-6 weeks
4. Surgical replacement of damaged valve or infected prosthetic valve