infective endocarditis

Question 1

What parts of the heart can be affected in infective endocarditis

Answer 1

infection of inner layer of heart
endocardium

heart valves:
native
prosthetic

interventricular septum
septal defect

chordae tendinae

intra-cardiac devices

Question 2

Why is infective endocarditis not a uniform disease

Answer 2

various presentations

possibly dependent on underlying cardiac disease

microorganism involved

presence / absence of complications

underlying patient characteristics

Question 3

What are the cardiac risk factors that can result in infective endocarditis

Answer 3

Native valve disease

Congenital heart disease  
   tetralogy of fallot 
  Ventral septal defect
  Patent ductus arteriosus 
  ASD - coarctation of aorta 

Rheumatic heart disease

Prosthetic heart valve surgery

cardiac surgery

prior native IE

Cardia hypertrophy

Question 4

What is the non cardiac risk factors for IE

Answer 4

IVDA

immunocompromised eg elderly/AIDS

diabetes mellitus

AIDS

trauma (burns)

indwelling medial devises

Question 5

What is the different mode of acquisition in bacteraemia IE

Answer 5

Health care related e.g.
Hospital, health care contact, IV therapy, nursing home

community acquired

IV drug abuse

Question 6

What is the signs of IE

Answer 6

Murmur
Muscoskeletal pain

splinter haemorrhages 
vasculitic rash
Roth Spots 
Osler’s nodes 
Janeway lesions
nephritis
anemia

Question 7

What is the symptoms of IE

Answer 7

Fever
fatigue
malaise 
Weight loss 
Headache

Question 8

What are features of patients with a high Index of suspicion of diagnosis of IE

Answer 8

fever

new murmur

pyrexia of unknown origin

known IE causative organism

prosthetic material

previous IE

congenital heart disease

new conduction disorder

immunocompromised

IV drug abuser

Question 9

When could signs of IE be absent

Answer 9

elderly

when prior antibiotic treatment has been given before IE was considered

immunocompromised

IE involving less virulent / atypical organisms

Question 10

What are the investigations for Infective endocarditis

Answer 10

Blood tests: 
 FBC - full blood count 
(neutrophilia)
CRP - C-reactive protein
ESR - erythrocyte sedimentation rate
Urea & electrolytes

Blood cultures
urinalysis

ECG

CXR

Echo

Question 11

What does the urea and electrolytes (blood test)indicate for in diagnosis of IE

Answer 11

nephritis
infection
sepsis

Question 12

What does ECG show in IE

Answer 12

conducting delay - due to abscess sitting on atrial ventricular septa

Question 13

What does a chest x ray show in infective endocarditis

Answer 13

Heart failure

Pulmonary abscesses

Question 14

What is the two types of echocardiogram

Answer 14

transthoracic (TTE)

+ transoesophageal (TOE

Question 15

When would you perform both atransthoracic (TTE)

+ transoesophageal (TOE)

Answer 15

When you have high clinical suspicion of infective endocarditis

Question 16

When would you perform a TOE

Answer 16

If TTE is positive:
To see complications and assesses
Measure size of vegetation

Poor quality TTE

Prosthetic valve intracardiac device present

If initial TOE negative but still have high clinical suspicion perform again within 7-10days

Question 17

When would you repeat an ECG in EI

Answer 17

If new complication arrises

To asses ongoing treatment

To asses treatment success on completion

Question 18

What could be the possible reasons of Infective endocarditis having a negative blood culture

Answer 18

Prior antibiotic treatment

Fastidious organism - only grow with specific nutrients

Intracellular bacteria

Question 19

Organisms can cause what types of IE

Answer 19

Native valve IE
IVDA IE
Prosthetic valve IE

Question 20

What is the pathogenesis of IE

Answer 20

damage to the endothelium with invasion and adherence of micro-organism to injured surface, proliferation then breaking of causing thrombotic endocarditis
= a sterile fibrin-platelet vegetation (abnormal mass)

Question 21

What is the organisms responsible for IE

Answer 21

Staphylococcus aureas - most common

Strepococci (Strep. Viridans)

Pseudomonase

aerguginosa

HACEK organisms

Fungi

Enterococci

Question 22

How do you test for the intracellular bacteria causing IE

Answer 22

serological testing, cell culture,
gene amplification,
PCR

Question 23

What is the major factors modified duke criteria for IE

Answer 23

Blood culture of IE positive
- + with 2 separate culture/ persistent

Evidence of endocardial involvement

• • ECG
• Valve murmur

Question 24

What is the minor factors in modified duke criteria

Answer 24

Predisposition
- heart condition/ drug use

fever

vascular/immunologic phenomena

Microbiological evidence
+ blood culture / serological evidence

Question 25

What is the criteria must be met from modified duke criteria for a definite diagnosis

Answer 25

2 major

1 major + 3 minor

5 minor

Question 26

What is the treatments for IE

Answer 26

Antibiotics - IV Aminoglycosides
best = bactericidal with shortened duration therapy

Surgery

Question 27

What does your choice of antibiotic depend upon

Answer 27

Received previous antibiotics

if its either native or prosthetic valve

When valve surgery was performed

local epidemiology

antibiotic resistance

specific culture negative pathogens

Question 28

What therapy is needed for slow growing dormant microbes

Answer 28

Prolonged antibiotic therapy eg 6 weeks +
+
removal of prosthetic material

Question 29

What is the antibiotic treatment of native valve IE

Answer 29

IV Gentamicin
1mg/kg 12 hourly

+ IV Amoxycillin
2g 4 hourly

{or vancomycin if if penicillin allergic, severe sepsis or MRSA}

Question 30

What is the antibiotic treatment for prosthetic valve IE

Answer 30

Gentamicin 
\+
IV Vancomycin 
\+  
Rifampicin

Question 31

What is the disadvantages of Gentamicin

Answer 31

nephrotoxic
ototoxic
dose must be measured to actual body weight

Question 32

What is the monitoring treatment with IE

Answer 32

blood tests daily

ECG every 1-2days

ECHO weekly

Question 33

What is the complications of IE

Answer 33

heart failure

fistula formation

leaflet perforation

uncontrolled infection

abscess formation

atrioventricular heart block

embolism

prosthetic valve dysfunction /dehiscence

Question 34

What is the most frequent and severe complication of IE, how is it shown

Answer 34

Heart failure - shown by refractory pulmonary oedema

Question 35

How do you know the in infection is uncontrolled

Answer 35

Persisting fever and positive blood cultures

Question 36

What is the cause of an uncontrolled infection

Answer 36

Inadequate antibiotic treatment

resistant organisms

Infected lines

extracardaic site of infection

adverse reaction to antibiotics

Question 37

How does abscess formation result in

atrioventricular heart block

Answer 37

If abscess in close proximity to base of septum innervates bundle of HIS and prevents conduction in the heart

Question 38

what is most likely to cause embolism in IE

Answer 38

Previous embolism
Multi-vascular IE
The size and mobility of vegetation
Increasing the antibiotic

Question 39

What is the most severe IE

Answer 39

prosthetic valve endocarditis

Question 40

What is the therapy for prosthetic valve endocarditis

Answer 40

removal recommended

and prolonged IV antibiotic course

Question 41

What is examples of prophylaxis

Answer 41

avoid extensive non-evidence-based use of antibiotics

Maintain good oral dental hygiene