infective endocarditis

Question 1

What is infective endocarditis (IE)?

Answer 1

An infection of the endocardium that typically affects one or more heart valves.
IE is often due to bacteremia.

Question 2

What are common causes of bacteremia leading to IE?

Answer 2

Dental procedures, surgery, distant primary infections, and non-sterile injections.

Question 3

What typically causes acute bacterial endocarditis?

Answer 3

Staphylococcus aureus.

Question 4

What is the most common cause of subacute bacterial endocarditis?

Answer 4

Viridans streptococci.

It usually affects individuals with preexisting heart valve damage.

Question 5

List some clinical features of infective endocarditis.

Answer 5

• Fatigue
• Fever
• Chills
• Malaise
• New or changed heart murmur
• Signs of heart failure
• Organ damage manifestations (e.g., glomerulonephritis, septic embolic stroke)

Question 6

What criteria are used to assess the likelihood of infective endocarditis?

Answer 6

The 2023 Duke-ISCVID criteria.

These criteria help in the diagnostic process.

Question 7

What is recommended for infective endocarditis prophylaxis?

Answer 7

Prophylaxis is recommended in specific circumstances, such as in patients with congenital heart disease undergoing certain dental procedures.

Question 8

HACEK group

Answer 8

Haemophilus spp.
Aggregatibacter actinomycetemcomitans
Cardiobacterium hominis
Eikenella corrodens
Kingella kingae

Question 9

causes of blood culture negative IE

Answer 9

Blood culture-negative IE is most commonly caused by antibiotic use before blood sample collection but can be due to pathogens that are difficult to culture.

Question 10

staphylococcus aureus IE

Answer 10

Approximately 35–40% of native valve IE cases
Most common cause of acute IE, including individuals who inject drugs and patients with prosthetic valves or pacemakers/ICDs
Typically affects healthy valves.
Usually fatal within 6 weeks if left untreated

Question 11

Viridans streptococci IE

Answer 11

Approximately 20% of native valve IE cases
Most common cause of subacute IE, especially in predamaged native valves (mainly the mitral valve)
Common cause of IE following dental procedures, respiratory tract incision and biopsy
Produce dextrans that facilitate binding of fibrin-platelet aggregates on heart valves

Question 12

Staphylococcus epidermidis IE

Answer 12

Less than 15% of native valve IE cases
Bacteremia from infected peripheral venous catheters
Common cause of subacute IE in patients with prosthetic heart valves, pacemakers, or ICDs

Question 13

Enterococci (especially Enterococcus faecalis) IE

Answer 13

Approximately 10% of native valve IE cases [3]
Multiple drug resistance
Common cause of IE following nosocomial UTIs
Causes native and prosthetic valve IE
Following gastrointestinal or genitourinary procedures

Question 14

Fungal endocarditis (Candida, Aspergillus fumigatus) IE

Answer 14

Less than 5% of native valve IE cases
At risk groups
Immunosuppressed patients (e.g., patients with HIV or organ transplant)
Individuals who inject drugs
Patients who have received cardiosurgical interventions
Patients with long-term indwelling IV catheters

Question 15

cardiac risk factors for IE

Answer 15

Acquired valvular disease (e.g., rheumatic heart disease, aortic stenosis, degenerative valvular disease)
Prosthetic heart valves
Congenital heart defects (e.g., VSD, bicuspid aortic valve)
Previous IE
Cardiac implantable electronic device (CIED)

Question 16

non-cardiac risk factors for IE

Answer 16

Poor dental status
Dental procedures
Nonsterile venous injections (e.g., in IV drug use)
Intravascular devices
Surgery
Chronic hemodialysis
Immunocompromise (e.g., HIV infection, diabetes)
Other bacterial infections (e.g., UTIs, spondylodiscitis, periodontal infection)

Question 17

most common infected valve in individuals who inject drugs

Answer 17

The tricuspid valve is the most commonly affected valve in individuals who inject drugs (associated with Pseudomonas, S. aureus, and Candida).
“Don’t tri drugs for the sake of your tricuspid valves.”

Question 18

most commonly infected valve in IE

Answer 18

mitral

Question 19

peripheral features of infective endocarditis

Answer 19

Question 20

tricuspid valve regurgitation sounds like

Answer 20

Holosystolic murmur that is loudest at the left sternal border
Seen in individuals who inject drugs, immunocompromised individuals, patients with congenital heart disease, and patients with instrumentation in the right heart (e.g., central venous catheters)

Question 21

mitral valve regurgitation sounds like

Answer 21

holosystolic murmur that is loudest at the heart’s apex and radiates to the left axilla

Question 22

cardiac manifestations of IE

Answer 22

tricuspid, aortic or mitral regurgitation
Heart failure (e.g., dyspnea, lower limb edema) due to valve insufficiency
Arrhythmias: Suspect a perivalvular abscess in patients with IE who develop a new conduction abnormality (e.g., heart block).

Question 23

which type of extra cardiac manifestations are you likely to get based on the location of the IE?

Answer 23

Extracardiac manifestations are typically caused by septic microemboli and/or immune complex precipitation and are more commonly seen in left-sided IE, with the exception of pulmonary embolic manifestations, which are more common in right-sided IE.
Vascular immunologic phenomena (e.g., Osler nodes, glomerulonephritis) are typically late manifestations of subacute bacterial endocarditis; they are less common in acute bacterial endocarditis given its rapid evolution.

Question 24

Roth spots

Answer 24

round retinal hemorrhages with pale centers

Question 25

osler nodes

Answer 25

painful nodules on pads of the fingers and toes caused by immune complex deposition

Question 26

laneway lesions

Answer 26

Small, nontender, erythematous macules on palms and soles Microabscesses with neutrophilic capillary infiltration and areas of hemorrhage caused by septic microemboli from valve vegetations

Question 27

emboli to intraabdominal organs

Answer 27

Acute renal injury: - Including hematuria and anuria - Due to renal artery occlusion or glomerulonephritis Splenomegaly and possible LUQ pain: - Due to splenic artery occlusion or splenic abscess - May lead to splenic rupture

Question 28

neurological manifestations of IE

Answer 28

(e.g., seizures, paresis): due to septic embolic stroke, hemorrhage, meningitis, encephalitis, and/or abscess

Question 29

pulmonary manifestations of IE

Answer 29

caused by septic emboli resulting from tricuspid valve involvement Signs of pulmonary embolism (e.g., dyspnea) Signs of pulmonary infection, e.g., multifocal pneumonia, lung abscess, and/or empyema.

Question 30

what should you do if IE is suspected

Answer 30

Take at least 3 sets of blood for culture because the pathogen is identified in about 90% of cases when 3 sets are taken. Take 2 sets immediately and take the third set at least 1 hour later. In patients with sepsis or septic shock, the priority is to start appropriate empirical antibiotic therapy as soon as possible, so all 3 sets of blood cultures should ideally be taken over a short time period before starting antibiotics. Blood cultures should ideally be taken from 3 separate venipuncture sites to avoid any misdiagnosis, in case one set is accidentally contaminated at the time of collection.

Question 31

which criteria should you use to justify the presence of endocarditis

Answer 31

2023 Duke-ISCVID criteria (on MD calc)

Question 32

lab findings in IE

Answer 32

leukocytosis raised inflammatory markers, but may also be normal urinalysis may show hematuria and/or nephritic sediment Up to 50% of patients with endocarditis have hematuria secondary to renal infarct and/or glomerulonephritis. troponin and BNP may be elevated

Question 33

choice of echo modality for IE

Answer 33

Transoesophageal echocardiogram (TOE) is significantly more sensitive in the diagnosis of infective endocarditis than transthoracic echocardiogram (TTE), due to poor visualisation of heart valves and device leads by TTE. In particular, TOE is more sensitive than TTE for prosthetic valve and cardiac implantable electronic device–associated endocarditis. If a TTE is negative in a patient with suspected prosthetic valve and cardiac implantable electronic device–associated endocarditis, arrange a TOE if possible.

Question 34

findings of IE on echo

Answer 34

Valvular vegetations: hyperechoic mobile masses located on the valve, mural endocardium, or prosthetic material [30] Abscess (e.g., perivalvular abscess ) New valvular regurgitation (especially in patients with valve prolapse, perforation, and/or destruction) New partial prosthetic valve dehiscence

Question 35

what additional imaging might be needed

Answer 35

to assess for complications cardiac CTA for diagnostic confirmation and/or assessment of valvular lesions CXR to evaluate for pulmonary infarcts abdominal US: if splenic abscess suspected MRI head: to assess for intracranial septic emboli

Question 36

empirical regimen for native valve endocarditis

Answer 36

benzylpenicilllin flucloxacillin gentamicin

Question 37

empirical regimen if MRSA is suspected, or for sepsis or septic shock, or for prosthetic valve endocarditis

Answer 37

vancomycin flucloxacillin gentamicin

Question 38

endocarditis caused my MSSA

Answer 38

flucloxacillin

Question 39

endocarditis caused by MRSA

Answer 39

vancomycin

Question 40

indications for surgery in IE

Answer 40

Prosthetic valve IE Valve dysfunction causing heart failure Uncontrolled infection (e.g., enlarging vegetation, persistent bacteremia) Perivalvular extension or complications (e.g., abscess, pseudoaneurysm, fistula, heart block) IE due to difficult to treat organisms (e.g., fungi, MDRO) High embolic risk (e.g., mobile vegetation ≥ 10 mm, recurrent embolism)

Question 41

surgical options

Answer 41

valve replacement or valve repair

Question 42

cardiac risk factors requiring IE prophylaxis for procedures

Answer 42

Presence of prosthetic cardiac valve or material History of endocarditis Certain types of congenital heart disease (CHD), e.g., unrepaired cyanotic CHD, repaired CHD (within 6 months of repair), repaired CHD with residual post-operative shunt or regurgitation Valvulopathy in cardiac transplant recipients

Question 43

types of procedures requiring IE prophylaxis

Answer 43

Some dental procedures including tooth extraction and routine dental cleaning Any invasive procedure involving respiratory tract or infected tissue (e.g., abscess drainage) Placement of a CIED Surgical placement of prosthetic cardiac or intravascular material (e.g., heart valve, intravascular graft)