Microbiology Infective Endocarditis and Bacteraemia Flashcards Preview

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Flashcards in Microbiology Infective Endocarditis and Bacteraemia Deck (35)
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1
Q

Definition

A
  • Bacterial (or fungal) infection of a heart valve or area of endocardium
  • Clinical presentation traditionally classified as either acute of sub-acute
  • Particular constellations of clinical signs and investigation results (diagnostic criteria) are required in order to make the diagnosis.
2
Q

Epidemiology: prevalence

A

2-6 per 100,000 population per year.

M=F

3
Q

Epi: Prognosis

A

Invariably lethal pre-antibiotics, it has still not gone away and may be on the increased in some categories of patients.
Still significant mortality (20%) and morbidity

4
Q

Epi Risk Factors

A
  • Risk factors and infecting organisms have changed over time, e.g. rheumatic fever was prime risk factor in up to 75% of cases in the pre-antibiotic era, but rare now.
  • Different organisms associated with different risk factors.
5
Q

Epi: Four categories

A
  • Native valve infective endocarditis
  • Prosthetic valve infective endocarditis
  • IVDU – associated endocarditis
  • Nosocomial infective endocarditis
6
Q

Native valve infective endocarditis

A
  • Congenital hear disease (high to lower pressure gradients greatest risk)
  • Rheumatic Heart Disease
  • Mitral valve prolapse
  • Degenerative valve lesions
7
Q

Native valve infective endocarditis organisms involved

A

Typically are viridans streptococci (oral flora) – streptococcus sanguis.

8
Q

Prosthetic Valve Endocarditis

A

1-5% of cases
Early (within first 2 months after surgery) or late
Coagulase negative staphylococci predominate

9
Q

IVDU – associated endocarditis

A

Median age 30 (M>F)
Right sided infection more common → because injection into venous system
Tricuspid 50%; Aortic 25%; Mitral 20%

10
Q

IVDU – associate endocarditis organisms

A

Staphylococcus aureus predominates, but other organisms, including fungi, sometimes responsible.

11
Q

Nosocomial infective Endocarditis → Incidence

A
Increasing Incidence (>10% in recent survey)
>60 years
12
Q

Nosocomial infective Endocarditis → Risks

A

Often underling cardiac disease
Intravenous lines, invasive procedures
Increasing right sided IE due to CVP lines and pulmonary artery catheters

13
Q

Nosocomial infective Endocarditis → Pathogenesis

A
  1. Heat defect leading to a pressure gradient across valve
  2. Fibrin platelet deposition and Bacteraemia
  3. Colonized fibrin-platelet deposit
  4. Further deposition of thrombus
  5. Vegetation occurs
14
Q

Nosocomial infective Endocarditis → Infecting organisms

A

Typical:
• 80% gram +ve – various fibrin binding proteins = sticky
• Ability to adhere and colonise damaged valves
• Staphylococcus aureus, Streptococcus sp,.
• Enterococci together are responsible for >80% of cases.
• Gram -ve

15
Q

Nosocomial infective Endocarditis →Immune system

A

• Inability of the immune system to eradicate the organisms once located on the endocardium

16
Q

Nosocomial infective Endocarditis →Host Factors

A
  • Pre-existing lesions of the layer of endothelial cells covering the valve or endovascular surface
  • Congenital cardiac abnormalities causing turbulent blood flows
  • Rheumatic fever resulting in valvular damage
  • Prosthetic valves
  • Sclerotic valves in elderly patients
  • Invasive procedures/intravascular lines.
17
Q

Nosocomial infective Endocarditis → Culture negative

A

➢ Q fever (Coxiella burnetti)
➢ Chlamydiae
➢ Brucella spp.

Therefore, if the diagnosis is suspected, a serum sample on admission and another 4 weeks later may be invaluable.

18
Q

Nosocomial infective Endocarditis → Transient Bacteraemia

A

➢ Chewing, tooth bruising, dental procedures → worse in the presence of gingivitis
➢ Medical and surgical procedures in non-sterile sites, e.g. urethral catheterisation, endoscopy.

19
Q

Nosocomial infective Endocarditis → Clinical Syndrome

A

Acute & Subacute
➢ Malaise (95%), pyrexia (90%), arthralgia (25%)
➢ Cardiac murmurs (90%), cardiac failure (5)
➢ Osler’s nodes (15%), Janeway lesions (5%)
➢ Splenomegaly (40%), cerebral emboli (20%)
➢ Haematuria (705)

20
Q

Nosocomial infective Endocarditis → Diagnosis

A

Pathological criteria

Clinical criteria

21
Q

Nosocomial infective Endocarditis →Pathological criteria

A

Microorganisms: demonstrated by cultre or histology in a vegetation, or in a vegetation that has embolised, or in an intracardiac abscess.

22
Q

Nosocomial infective Endocarditis →Pathological lesions

A

Vegetation or intra-cardiac abscess present, confirmed by histology showing active endocarditis.

23
Q

Nosocomial infective Endocarditis →Possible Infective Endocarditis

A

Findings consistent with IE that fall short of “Definite” but are not rejected

24
Q

Nosocomial infective Endocarditis → Rejected

A

Film alternative diagnosis for manifestations of endocarditis, or resolution of manifestations with antibiotic therapy of 4 days or less. Or no pathological evidence of IE at surgery or autopsy after antibiotic therapy for 4 days or less.

25
Q

Nosocomial infective Endocarditis →Clinical Criteria – Major criteria

A
  1. Possible blood culture
    ➢ Typical organisms for IE from 2 separate blood cultures
    ➢ Persistently positive blood cultures
  2. Evidence of endocardial involvement
26
Q

Nosocomial infective Endocarditis → Evidence of endocardial involvement

A
Positive echocardiogram
➢	Vegetation’s
➢	Abscess
➢	New partial dehiscence of prosthetic valve
➢	New valvular regurgitation
27
Q

Minor Criteria

A
➢	Predisposition – heart conditions/IVDA
➢	Fever >/=38oc
➢	Vascular phenomena
➢	Immunological phenomena
➢	Microbiological evidence
➢	Echocardiogram
28
Q

Vascular Phenomena

A

Major arterial emboli, septic pulmonary infarcts, intracranial haemorrhage, Janeway lesions

29
Q

Immunological phenoma

A

Glomerulonephritis, Oslers nodes, Roth spots, Rheumatoid factor

30
Q

Microbiological evidence

A

Positive blood culture but not meeting major criteria opposite

31
Q

Echocardiogram

A

Consistent with IE but not meeting major criteria opposite

32
Q

Complications

A
Valvular destruction leading to cardiac failure
Surgery if indicated:
➢	Extensive damage to valve
➢	Infection of prosthetic valve
➢	Worsening renal failure
➢	Persistent infection but dailure to culture organisms=
➢	Embolisation
➢	Large vegetation’s
Embolization – cerebral, pulmonary
Acute renal failure – secondary to IE or to treatment – aminoglycosides.glycopeptides
Mycotic aneurysms
Death
33
Q

Treatment Principles

A

Diagnosis with microbiobial confirmation

Antibiotics

34
Q

Q Fever

A

tetracyclines, co-trimoxazole
➢ Year therapy
➢ Valve replacement

35
Q

Chlamydiae

A

Tetracyclines

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