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Medical Microbiology and Virology > 38 Cardiology infections > Flashcards

38 Cardiology infections Flashcards

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1
Q

IE involves endothelial linings of the heart, usually including heart valves. Majority have pre-existing heart defect e.g rheumatic fever/ congenital/ prosthetic valve/ cardiac device

How do vegetations form?

A

Route of entry into bloodstream e.g dental work, urinary tract, GI tract

Organisms bind to fibrin-platelet vegetations on damaged valves/ endothelium

Multiply further, as protected by vegetation

Slow process, so from bacteraemia to symptoms can take 5 weeks

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2
Q

Which organisms cause native valve IE?

Most commonly affects aortic/ mitral valves

30% of infections can be classified as HAI - due to lines/ procedures

A

Staph aureus 30%
Coagulase negative staph 5%

Streptococci -

  • viridans species - mutans/ sanguinis/ mitis 40%
  • Group D - enterococcus 10%

Gram neg rods 5%
HACEK 5%
Candida

Culture negative 5-25%

Staph aureus is the most common in IVDU 70%

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3
Q

What are less common causes of native valve IE?

blood culture negative

A

Strep pneumoniae
Coagulase negative staph

If blood cultures negative test for -
Haemophilus influenzae
Brucella
Bartonella
Coxiella
Chlamydia
Legionella
HACEK (if grown in wrong medium)
Trephonema whipplei
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4
Q

What are causes of prosthetic valve IE?

Often divided into early (within 1 year of insertion) and late infection. There are microbiological differences in aetiology

A

Staph epidermidis 30%
Staph aureus 40%
Strep viridans <5%

Pseudomonas

Serratia marcescens

Diptherioids

HACEK

Fungi

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5
Q

Most patients with IE with have fever and murmur.

What are the modified duke criteria?

A

Major -

  • typical organism demonstrated in culture or in vegetation in 2 separate blood cultures - Staph/ Strep/ HACEK
  • one positive blood culture for coxiella burnetti
  • vegetation showing endocardial involvement

Minor -

  • fever
  • predisposition - IVDU, predisposing heart condition
  • vascular phenomena - Janeway lesions, septic emboli Splinter haemorrhages
  • immunologic phenomena - Oslers nodes, Roth spots, glomerulonephritis (haematuria)
  • microbiological evidence - blood culture is not typical for IE

Definite IE -
2 major
1 major 3 minor
5 minor

Possible IE -
1 major 1 minor
3 minor

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6
Q

What are investigations for IE?

A

Blood cultures - 3 sets, at different sites, with 6 hours between them

Urinalysis - haematuria

TTE/ TOE

Consider investigation for rarer organisms

May need PET/CT scan - look for uptake around valves. Only use if prosthetic valve been in situ for >3 months

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7
Q

IE has mortality rate between 20-50%, why is this?

A

Late presentation

Vegetation resistant to host defenses/ antibiotics

Vegetation has high bacterial desnity

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8
Q

What is treatment for IE?

Native valve - indolent presentation

Native valve - sepsis

A

Native valve - indolent presentation

  • Amoxicillin 2g 4 hourly
  • gentamicin 1mg/kg BD

Native valve - sepsis

  • vancomycin
  • gentamicin 1mg/kg BD
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9
Q

What is treatment for IE?

Prosthetic valve

A

Vancomycin

Gentamicin 1mg/kg BD

Rifampicin 600mg PO/IV BD

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10
Q

Proven Staphyloccal endocarditis (MSSA)

What is treatment?

Native valve

Prosthetic valve

A

Native valve
- flucloxacillin 2g IV QDS

Prosthetic valve

  • flucloxacillin 2g QDS
  • gentamicin 1mg/kg BD
  • rifampicin 600mg BD

Switch flucloxacillin for vancomycin if MRSA

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11
Q

Proven Streptococcal endocarditis

What is treatment?

Native valve/ prosthetic valve is the same

A

Benzylpenicillin 1.2g 4 hourly

or

Ceftriaxone 2g OD - suitable for OPAT

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12
Q

Proven enterococcal endocarditis

What is treatment?

A

Amoxicillin 2g 4 hourly
Vancomycin if resistant - enterococci usually are

+

Gentamicin 1mg/kg BD

Swap amoxicillin for vancomycin if penicillin allergic

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13
Q

Coxiella burnetti is rare cause of IE

What are treatment options?

Treatment required for approx 3 years, depending on antibody response

A

Doxycyline + hydroxychloroquine

Doxycycline + ciprofloxacin

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14
Q

Proven candida endocarditis.

What are treatment options?

A

Caspofungin

or

Ambisome (amphotericin B
+
Flucytosine

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15
Q

Proven aspergillus endocarditis

What are treatment options?

A

Voriconazole (monitor levels)

or

Ambisome (amphotericin B
+
Flucytosine

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16
Q

Up to 50% of patients with IE will require cardiac surgery.

What are indications?

A

Any IE with existing prosthetic mateiral

Heart failure - severe regurgitation causing pulmonary oedema

Uncontrolled infection - abscess, aneurysm, persisting fever >10 days

Large vegetations - can cause embolic episodes should be removed

17
Q

Sometimes antibiotics are required a prophylaxis in dental procedures.

Who is recommended to have prophylaxis?

Give amoxicillin 2g oral or clindamicin 600mg, 30-60min before procedure

A
  1. Previous endocarditis
  2. Valve (any) replacement
  3. Right to left shunts (e.g. cyanotic congenital heart disease)
  4. Or on the specific recommendation of consultant cardiologist following formal letter advising as such.

No prophylaxis for bronchoscopy/ endoscopy

18
Q

What is typical duration of antibiotic therapy for IE?

A

4-6 weeks IV from date of negative blood culture

6 weeks IV from date of cardiac surgery, if valve culture was positive

Can be via OPAT

POET trial showed oral can be option for selected groups

19
Q

Gentamicin dosing,

What levels should peak/ trough be?

A

trough <1mg/l

peak 3-5mg/l

20
Q

Pericarditis and myocarditis can be caused by various pathogens.

What are the most common ones?

A 
Viral -
echovirus
Enterovirus
Coxsackie A + B
CMV
HBV
EBV
HIV
Bacteria
Staph aureus 
Strep pneumoniae
Mycoplasma
TB
Other causes
post-MI
post-cardiac surgery
uraemia
drug induced
trauma
21
Q

With myocarditis/ pericarditis, what are risk factors necessitating admission?

A

Fever
Large pericardial effusion/ tamponade
Lack of response to aspirin/ NSAIDs

22
Q

Which organism is associated with IE in context of bowel cancer?

A

Group D streptococcus - S gallolyticus (S Bovis)

Recommend colonoscopy. If negative, suggest repeat in 6 weeks time

23
Q

If cardiac device being implanted, the perioperative antibiotics are given.

If patient is recovering from infection, how long should they wait before have cardiac device inserted?

A

2 weeks after infection

24
Q

Which organisms are included in HACEK group?

  • gram-negative coccobacillary organisms
  • fastidious growth
  • typically oropharyngeal commensals, but also GI/GU tract. So dental disease most common route of infection
A 
Haemophilus species
Aggregatibacter species
Cardiobacterium hominis
Eikenella corrodens
Kingella species

The HACEK group accounts for approximately 5%-10% of community-acquired native-valve endocarditis

25
Q

How does treatment differ in HACEK IE?

A

Generally resistant to ampicillin

Ceftriaxone is usual treatment

26
Q

CT scan incidentally shows splenic infarcts.

What is significance of this?

A

Can indicate IE with septic emboli

27
Q

Up to 30% patients with IE develop renal failure.

Why is this?

A

Drug induced

Immune complex deposition

Renal infarction - micro emboli

Under-perfusion - heart failure

28
Q

Patient with PPM, presents with fever, raised CRP.

ECHO shows no vegetations. Suspecting device infection.

What is treatment?

A

Remove device

Flucloxacillin + rifampicin
6 weeks

Rifampicin helps with biofilms
Switch flucloxacillin to vancomycin in MRSA suspected

Medical Microbiology and Virology (60 decks)

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