Bacterial Endocarditis

Question 1

What is endocarditis?

Answer 1

Infection of the lining of the heart and the cusps of cardiac valves

Question 2

What causes endocarditis?

Answer 2

Microorganisms adhering and multiplying on inner most chambers of the heart and it’s valves

Question 3

What side of the heart does endocarditis predominantly affect?

Answer 3

The left side

Question 4

What is a common cause for right sided endocarditis?

Answer 4

IV drug abuse

Question 5

What are some of the risk factors for endocarditis (7)

Answer 5

• Congenital valve disease
• Ventricular septal defects
• Rheumatic heart disease
• Mural thrombus
• Central venous line
• Valvular/cardio surgery
• IV drug abuse

Question 6

What is the pathophysiology of endocarditis?

Answer 6

1. Microbes enter a blood vessel through an abscess or during dental surgery or very vigorous teeth brushing
2. They latch onto heart valves that are already damaged (e.g. sclerosis).
3. Adhesion and aggregation of platelets and fibrin forms a clot or vegetation

The local inflammation leafs to expression of transmembrane protein that binds fibronectin–> all of this makes it easier for the bacteria to bind

Question 7

What are some of the early manifestations?

Answer 7

Low grade fever
Heart murmur (new or changed)
Fatigue
Malaise

Question 8

What are some of the main points that would make you suspect IE?

Answer 8

• New prosthetic valve
• Embolic event of unknown origin
• Sepsis of unknown origin
• Haematuria

Question 9

What are some of signs associated with development of micro emboli and immune complex deposition?

Answer 9

Splinter haemorrhages
Janeway lesions
Oslers nodes
Roth spots 
Glomerulonephritis.

Question 10

What investigations can be done?

Answer 10

• Blood cultures- ideally 3 before starting Abx to ensure right sensitivities have been identified
• Echocardiography (trans thoracic or trans esophogeal)
• CXR
• ECG
• Urine microscopy
• Inflamm markers
• FBC, U+E’s, LFT’s

Question 11

What are the most common bacteria that cause IE?

Answer 11

Gram positive: Streptococci (mouth) staph aureus (skin)

Question 12

What are the main gram negative bacteria that can cause IE?

Answer 12

HAECK group bacteria

Question 13

Can IE be caused by fungal microorganisms?

Answer 13

Yes, but it is very rare and is associated with higher mortality as it’s often missed

Question 14

How is a diagnosis confirmed?

Answer 14

Using Duke’s criteria which has major and minor criteria.

Question 15

What are the major critieria?

Answer 15

• Microbiologic evidence of an organism that’s likely to cause infective endocarditis.
• Seeing evidence of endocardial disease: new valvular regurgitation, or an echocardiogram showing a vegetation, abscess, or partial dehiscence of a prosthetic valve.

Question 16

What are the minor criteria?

Answer 16

• Predisposing factor, like a known cardiac lesion or history of recreational drug injections
• Fever
• Evidence of septic emboli, like arterial emboli, pulmonary infarcts, Janeway lesions, or conjunctival hemorrhage
• Autoimmune conditions like glomerulonephritis, Osler’s nodes, Roth’s spots, or even a positive Rheumatoid factor
• Microbiologic or serologic evidence that doesn’t satisfy a major criteria.