Infective Endocarditis

Question 1

Define infective endocarditis.

Answer 1

Infection of inner layer of heart (endocardium). It also affects the heart valves (whether native or prosthetic) and inter ventricular septum (septal defect), chordae tendon and intra-cardiac devices.

Question 2

How has the incidence of infective endocarditis changed over the past thirty years?

Answer 2

Incidence ad mortality have not changed.

Despite major advances/therapeutic produces - poor prognosis and high mortality.

Question 3

Why can’t infective endocarditis be described as a uniform disease?

Answer 3

Various presentations, dependent on: underlying cardiac disease, microorganism involved, presence/absence of complications, underlying patient characteristics.

Question 4

What people might be involved in the management of a patient with infective endocarditis?

Answer 4

Primary care physicians/acute medicine, cardiologists, surgeons, microbiologists, infectious disease.
(neurologists, neurosurgeons, radiologists, pathologists).

Question 5

What are the possible classifications of infective endocarditis?

Answer 5

Acute, subacute, chronic.

Question 6

In which gender is infective endocarditis more common?

Answer 6

2x more common men, but worse prognosis in women.

Question 7

What is the incidence of IE?

Answer 7

3-10 episodes/100,000 person-years general population and 14.5 episodes/100,000 person-years in 70-80 year olds.

Question 8

What was the epidemiology of IE previously like?

Answer 8

Previously seen in young adults with well defined valve disease (mostly rheumatic valve disease). More chronic/subacute.

Question 9

How has epidemiology changed?

Answer 9

Earlier diagnosis, more acute presentations, changes in micro profile, prophylaxis (conflicting recommendations).

This means IE now seen in older patients (mostly due to degenerative AS). No. of rheumatic heart disease cases dropped to <20%. Mostly health-care associated, due to invasive procedures and intracardiac devices.

Question 10

What sort underlying conditions or behaviours put people more at risk of IE?

Answer 10

Prosthetic valves, mitral valve prolapse, bicuspid aortic valve, congenital heart disease, IV drug abuse.

Question 11

What are the common organisms responsible for causing IE in IVDAs?

Answer 11

Staph aureus, CNS, beta-haemolytic strep, fungi, aerobic gram -ve bacilli (incl. psuedomonas), polymicrobial.

Question 12

What are the common organisms responsible for causing IE in patients with indwelling medical devices?

Answer 12

Staph aureus, CNS, beta-haemolytic strep, fungi, aerobic gram -ve bacilli, corynebacterium spp.

Question 13

What are the common organisms responsible for causing IE in patients with diabetes mellitus?

Answer 13

S. aureus, beta-haemolytic strep, strep pneumoniae.

Question 14

What are the common organisms responsible for causing IE in patients with AIDS?

Answer 14

Salmonella spp, S. pneumoniae, S. aureus.

Question 15

What are the common organisms responsible for causing IE in patients with chronic skin infections or burns?

Answer 15

Staph aureus, beta-haemolytic strep, fungi, aerobic gram -ve bacilli.

Question 16

What are the common organisms responsible for causing IE in patients with genitourinary infection or manipulation incl. pregnancy, abortion, delivery?

Answer 16

Enterococcus spp, group B strep, listeria monocytogenes, aerobic gram -ive bacilli, neisseria gonorrhoeae.

Question 17

What are the common organisms responsible for causing IE in patients with alcoholic cirrhosis?

Answer 17

Bartonella spp, aeromonas spp, listeria spp, S. pneumoniae, beta-haemolytic strep.

Question 18

What are the common organisms responsible for causing IE patients with gastrointestinal lesions?

Answer 18

Strep bovis, enterococcus spp, clostridium septicum.

Question 19

What are the common organisms responsible for causing IE in patients undergoing solid organ transplant?

Answer 19

S. aureus, asperigllus fumigatus, candida spp, enterococcus spp.

Question 20

What are the common organisms responsible for causing IE in the homeless (with body lice)?

Answer 20

Bartonella spp.

Question 21

What are the common organisms responsible for causing IE in patients with pneumonia/meningitis?

Answer 21

S. pneumoniae.

Question 22

What are the common organisms responsible for causing IE in people who’ve come into contact with containerised milk or infected farm animals?

Answer 22

Brucella spp, pasteurella spp, coxiella burnetii, erysipelothrix spp.

Question 23

What are the common organisms responsible for causing IE in people after dog/cat exposure?

Answer 23

Bartonella spp, pateurella spp, C. septicum.

Question 24

Describe the pathophysiology of IE.

Answer 24

Adherence and invasion of nonbacterial thrombotic endocarditis (a sterile fibrin-platelet vegetation).

Causing mechanical disruption of valve endothelium (turbulent blood flow/Venturi effect, electrodes, catheters, inflammation (rheumatic carditis), degenerative changes) all favour infection by most types of organism.

Physically normal endothelium - 25% (local inflammation).

Question 25

Describe the venturi effect.

Answer 25

The reduction in fluid pressure that occurs when a fluid flows through a constricted section of pipe.

Question 26

Describe the steps of bacterial colonising the damage epithelium leading to IE.

Answer 26

Exposed stream cells and ECM proteins trigger deposition of fibrin-platelet clots to which strep bind. This attracts monocytes and induce them to produce tissue factor activity and cytokines. These mediators active coagulation cascades, attract and activate blood platelets, and induce cytokine, integral and TFA production from neighbouring endothelium encouraging vegetation growth.

Not done!!!!!!!!!