Infective Endocarditis and other cardiac infections

Question 1

What does it mean if bugs are present in the blood?

Answer 1

Bacteraemia or septicaemia - any presence of bugs is a bad thing as blood is usually sterile

Question 2

Why does blood culture collection have to be sterile?

Answer 2

To ensure that any bacteria present in the culture is in the blood and not simply due to poor technique

Question 3

What questions must be thought of when a blood culture comes back positive?

Answer 3

What is the usual habitat of the organism?
What diseases is this organism associated with?
What is the optimum antimicrobial management required?

Question 4

What is infective endocarditis?

Answer 4

Infection of the endothelium of the heart valves

Question 5

What is the epidemiology of infective endocarditis?

Answer 5

Approximate incidence 1 per 1000 hospital admissions
Increasing mean age (majority >50 years)
Hospital acquired cases are increasing, particularly due to staphylococcus aureus

Question 6

What can predispose people to infective endocarditis?

Answer 6

Heart valve abnormality (calcification/sclerosis in elderly, congenital heart disease, post rheumatic fever)
Prosthetic heart valve
IV drug users
IV lines

Question 7

What is likely to form over a prosthetic valve?

Answer 7

A biofilm

Question 8

What is the pathogenesis of endocarditis?

Answer 8

Heart valve damaged
Turbulent blood flow over roughened endothelium
Platelets / fibrin deposited
Bacteraemia (may be transient) e.g. from a dental treatement
Organisms settle in fibrin / platelet thrombu becoming a microbial vegetation

Question 9

What can happen to infected vegetations?

Answer 9

They are friable and can break off, becoming lodged in the next capillary body they encounter causing abscesses or haemorrhage (may be fatal)

Question 10

What side of the heart is more likely to be affected by infective endocarditis?

Answer 10

Usually the left side of the heart

Question 11

What organisms are most likely to cause infective endocarditis?

Answer 11

Staph aureus (38%) 
Viridans Steptococci (31%) 
Enterococcus sp (8%) 
Staph epidermis (6%)

Question 12

What are examples of unusal organisms to cause endocarditis?

Answer 12

Atypical organisms (do serelogy test) - bartonella, coxiella burnetti (Q-fever), chlamydia, legionella, mycoplasma, brucella
Gram-negatives - HACEK
Fungi

Question 13

What are HACEK organisms?

Answer 13

Haemophilus spp, aggregatibacter spp, cardiobacterium, eikenella, kingella

Question 14

What are the major critera (according to dukes) for infective endocarditis?

Answer 14

2 separate positive blood cultures with microorganisms typical of infective endocarditis: viridans strep, step. bovis, HACEK, staph. aureus, CA enterococci
Echo evidence
New valvular regurg

Question 15

How are staph infections treated?

Answer 15

Flucloxacillin

Question 16

How are strep infections treated?

Answer 16

Penicillins

Question 17

What is the most common coagulase negatiev staph?

Answer 17

Staph. Epidermis

Question 18

Where are you likely to find staph. epi?

Answer 18

Often a skin contaminant, BUT can infect prostetic material (IV line, prosthetic heart valves/joints)

Question 19

What colour is staph aureus on a blood culture?

Answer 19

Golden (beta haemolysis)

Question 20

What are the presenting symptoms of acute endocarditis?

Answer 20

Presents as overwhelming sepsis and cardiac failure

Usually due to aggressive (virulent) organisms such as staph. aureus

Question 21

What are the presentations of subacute endocarditis?

Answer 21

Fever
Malaise
Weight loss
Tiredness
Breathlessness - cardiac failure if it embolises to the lungs

Question 22

What are the clinical signs of subacute endocarditis?

Answer 22

Fever
New or changing heart murmur
Finger clubbing
Splinter haemorrhages
Splenomegaly 
Roth spots - in eyes
Janeway lesions - not painful
Osler nodes (osler = ouch) 
Microscopic haemoaturia

Question 23

What can cause early prosthetic valve endocarditis?

Answer 23

Early (usually within 60 days), usually infected at the time of valve insertion and usually due to staph. epidermis or staph, aureus

Question 24

What can cause late prosthetic valve endocarditis?

Answer 24

Up to many years after valve insertion - due to co-incidental bacteraemia. There is a wide range of possible organisms

Question 25

What is the antibiotics treatment for prosthetic valve endocarditis?

Answer 25

Vancomycin
Gentamicin
Rifampicin

Question 26

What is likely to the be the cause of endocarditis in PWID?

Answer 26

right sided endocarditis (tricuspid valve)
Usually staph. aureus
Can cause septic emboli in the lungs (commonly mistaken for pneumonia)

Question 27

What is the treatment for native valve endocarditis (viridans step)

Answer 27

Amoxicillin and gent

Question 28

What is the treatment for drug user endocarditis?

Answer 28

Flucloxacillin

Question 29

What is the treatment for viridans strep?

Answer 29

Benzylpenicillin and gent

Question 30

What is the treatment for enterococcus sp?

Answer 30

Amoxicillin/vancomycin and gent

Question 31

How is the treatment of endocarditis monitored?

Answer 31

IV antibiotics usually given for 4-6 weeks
Monitor cardiac function, temperature and serum C-reactive protein (CRP)
If failing on antibiotic therapy then consider referral for surgery early

Question 32

What are the symptoms of myocarditis?

Answer 32

Fever
Chest pain
SOB
Palpitations

Question 33

What are the signs of myocarditis?

Answer 33

Arrhythmia

Cardiac failure

Question 34

Who is most likely to get myocarditis?

Answer 34

More common in young people (cause of sudden death)

Question 35

What are the most likely causes of myocarditis?

Answer 35

Mainly caused by enteroviruses - coxsackie A and B and echo virus

Question 36

How are enteroviruses diagnosed?

Answer 36

Diagnosedd by viral PCR. Throat swab and stool for enteroviruses. Throat swab for influenza
Supportive treatment

Question 37

What is the main feature of pericarditis?

Answer 37

Chest pain

Commonly secondary to myocarditis