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Year 3 Academic Weeks > A1 - Bacteraemia/Endocarditis > Flashcards

A1 - Bacteraemia/Endocarditis Flashcards

1
Q

What is Bacteraemia?

A

The presence of viable bacteria in the blood stream

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2
Q

What is Bloodstream Infection?

A
  • Bacteraemia with recognised pathogen plus clinical signs of infection.
  • Sometimes used interchangeably with bacteraemia
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3
Q

What is Sepsis?

A
  • Life-threatening organ dysfunction caused by a dysregulated host response to infection
  • Infection with evidence of organ dysfunction
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4
Q

Bacteraemia can be in sterile sites and non-sterile sites?

What is the difference?

A

Sterile sites: No resident bacteria; isolation of any bacteria from these compartments is significant. These should be taken seriously

Non-sterile sites: Host to multitude of organisms of varying pathogenicity; isolation may represent colonisation only. Represents colonisation. Commnesal

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5
Q

Examples of bacteraemia in sterile sites?

A
  • Blood
  • Central nervous system
  • Pleural, peritoneal, pericardial, synovial fluid
  • Bone marrow
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6
Q

Examples of Bacteraemia in non-sterie sites?

A

Lower intestine

  • Urinary tract
  • Skin
  • Oropharynx/upper-respiratory tract
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7
Q

Name some common microorganisms that cause bacteraemia?

A
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8
Q

Why is it important to treat bacteraemia?

A

There is high risk of progression to sepsis.

Delay in appropriate antibacterial treatment associated with rapidly increasing risk of death

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9
Q

Classificaiton by site

What is the difference between extravascular and intravascular infections?

A

Extra: Infection located outside of the cardiovascular system. Indirectly goes through the lymphatic system and causes bactraemia

Intra: Infection located inside the cardiovascular system

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10
Q

How can intravascular infection be further classified?

A

Vascular Infections - infection of the blood vessels. less common but very serious.

Intravascular catheter related infection- MC

Infective endocartitis

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11
Q

Bacteraemia

Common source of infection?

A
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12
Q

Other sources of bacteraemia can be transient causes

Think of some examples?

A
  • Flossing, dental procedures, other activities of daily living…
  • Tooth brushing – approx. 20%
  • Flossing – approx. 20%
  • Partuition – approx. 10%
  • Defaecation – approx. 5%
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13
Q

WHat are the different patterns of bacteraemia?

A
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14
Q

How do you diagnose bacteraemia?

A

Through blood cultures (venous sample)

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15
Q

Blood cultures essential for the diagnosis of bloodstream infection (BSI).

2 blood cultures in __-hr will detect ~90% of BSI; __ sets may be needed to detect >99% of BSIs.

Sample prior to antibiotics if possible to maximise yield. Sampling using strict aseptic technique to avoid _____________.

A

Blood cultures essential for the diagnosis of bloodstream infection (BSI).

2 blood cultures in 24-hr will detect ~90% of BSI; 4 sets may be needed to detect >99% of BSIs.

Sample prior to antibiotics if possible to maximise yield. Sampling using strict aseptic technique to avoid contamination.

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16
Q

When can you get a false positive blood culture?

How do you prevent this?

A

WHen you get a blood culture, the neddle goes through the skin. Microorangisms might be on the skin that enter through the needle which would show you a positive result when actually they arent in the blood.

strict non touch aseptic technique to avoid contamination

17
Q

What happens after taking a blood sample (bacteraemia)?

A
  • at the bottom of the blood culture bottle there is a pH sensor which can cause a change in colour
  • they enter automated machines (silos). these will detect whether they are positive or negative.
  • then you take a sample and do a gram stain

- place it in an agar plate. Where there is a high inhibition zone the better/effective the antibiotic

18
Q

you have two bottles of blood culture

Why?

A

one bottle is in aerobic condition

one bottle is in anaerobic conditon

19
Q

Think carefully before dismissing positive blood culture as contaminant if patient at risk for infection with skin flora organism

Examples are?

A

e.g. prosthetic heart valve, long-term vascular access device

20
Q

What is the pattern of bacteraemia?

A

Transient bacteraemia: • Lasts minutes or hours. • Usually secondary to a procedure at a non-sterile site e.g. gastric biopsy, toothbrushing.

Intermittent bacteraemia: • Can occur from infections such as abscesses, also osteomyelitis, pneumonia. EXTRAVASCULAR

Persistent bacteraemia: • Usually an intravascular infection e.g. Infective Endocarditis, vascular graft infection. • Sometimes also early stages of systemic infections e.g. Salmonella Typhi

21
Q

What antibacterial treatment should you use?

A

Start SMART Empirical treatment based on suspected source of infection or broadspectrum cover if source unknown. Aim to cover likely spectrum implicated pathogenic bacteria. Consider: severity of illness; risk of resistant organisms (treatment and travel history)

Then FOCUS Targeted treatment: Narrowest spectrum antimicrobial, with confirmed effectiveness against isolated organism(s), able to penetrate site of infection. May initially modify treatment based on Gram stain before selecting definitive treatment based on susceptibility results.

22
Q

What is infective endocarditis

A

Infective endocarditis, also called bacterial endocarditis, is an infection caused by bacteria that enter the bloodstream and settle in the heart lining, a heart valve or a blood vessel. IE is uncommon, but people with some heart conditions have a greater risk of developing it

23
Q

Patho of Infective Endocarditis?

A
  • arises when there is structural heart abnormality that affects cardiac valves
  • this can be caused by things like congenital heart disease, accquired heart disease, ASD, VSD
  • Endocardial injury will lead to
  • platelet deposition/aggregration and eventually cause fibrin matrix
  • Microbial ahesion
24
Q

Infective Endocarditis: Risk factors

For Endocardial Damage

A

Congenital heart disease

• e.g. Bicupsid valves, ventricular septal defect, Tetralogy of Fallot

Acquired heart disease

• e.g. Rheumatic heart disease, degenerative valve disease, prior endocarditis

Intracardiac prosthetic material

• Valve replacements, pacemakers, defibrillators

25
Q

Infective Endocarditis: Risk factors

For Bacteraemia

A
  • Injecting drug use
  • Long-term intravenous catheters - e.g. haemodialysis lines
  • Invasive procedures
26
Q

How does infective endocarditis affect the rest of the body?

Heart

Brain

Kidney

Skin

Sepsis

A
27
Q

What does FUO mean?

A

Fever of unknown origin

28
Q

What are the clasical clinical features of infective endocardits?

A
29
Q
A
30
Q

What are the actual clinical features?

A
  • Over the last 50 years, shift from rheumatic to degenerative heart disease as main predisposing structural abnormality.
  • Earlier presentation means less time for development of classical embolic and immunological features.
  • Increasing proportion due to health-care associated exposure (i.e. long-term venous catheters) or injecting drug use.
31
Q

What is the criteria used for infective endocarditis?

A

Duke diagnostic criteria.

32
Q

Whta is Duke diagnostic criteria?

A

you need presistent positive blood cultures and evidence of endocardial involvement.

33
Q

Ix for IE

A
  1. Peripheral Blood Cultures-≥3 sets
  2. Arrange echocardiogram
  3. ECG & chest-x-ray
34
Q

classification of IE

A
35
Q

Aetiology of IE

A
36
Q

Antimicrobial treatment for IE

A

high doeses of antibiotics for prolong duration

Year 3 Academic Weeks (40 decks)

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