Vascular Infections Flashcards
What is a vascular infection?
Infection where the source of infection in the heart of vascular system
What is the most important infection test for diagnosing invasive infection?
Blood cultures
What is bacteraemia?
Not a diagnosis, just means bacteria has been detected in the blood
What 2 components are required for the diagnosis of a bloodstream infection?
Bacteraemia + symptoms/signs of infection
Bacteraemia can be defined by the timing of bacteria presence in the blood. What are the 3 types?
- Transient
- Intermittent
- Continuous
What is transient bacteraemia?
Typically in bloodstream for minutes/hours before being cleared, often harmless and asymptomatic
(shown by peak 1)
What is intermittent bacteraemia? What type of infections can it be seen in?
Bacteria appear in bloodstream, are cleared and then appear again e.g. pneumonia, pyelonephritis, abscess, meningitis
Shown by peak 2
What is continuous bacteraemia? What type of infections can it be seen in?
Bacteria is detected every time blood cultures are taken e.g. endocarditis, mycotic aneurysm, pacing lead infection, infected DVT
Shown by line 3
Why should you not wait to sample blood until temp >38 degrees?
As this may not be the point where there is a peak in the number of bacteria in the blood - look for other symptoms e.g. confusion, tachycardia, haemodynamic instability, cold & shivery
What is a high temperature usually caused by?
High temperature is often due to the inflammatory response that occurs as a result of many organisms
What should you do (if you have time) before giving IV antibiotics in a patient presenting with an infection?
Take blood cultures
What is a CRBSI?
Intravascular Catheter-Related Bloodstream Infection
What are the 4 main routes of colonisation in a CRBSI?
- At time of insertion; ‘exit site’
- Via hub contamination (infection migrates down the lumen of the line)
- Haematogenous (bacterial and fungi get into blood stream via other source)
- Via infusion
Which bacteria is the most common cause of CRBSI?
Coagulase negative staphylococci 31%
- Normally live on skin harmlessly, most common type
- Skin breach can lead to infection
- Can be due to bad handwashing
4 most common organisms causing CRBSI?
- Coagulase negative staphylococci 31%
- Staphylococcus aureus 20%
- Coliforms 13% e.g. E. coli
- Candida 9%
A patient presenting with which 3 features should be considered for CRBSI?
- Intravascular catheter
- Systemic signs of infection e.g. fever, confusion
- Bacteraemia or fungaemia
What is an indirect way of diagnosing CRBSI?
Clinical signs of infection that resolve on catheter removal
What would the same organism detected in at least 1 peripheral blood culture AND the catheter tip indicate?
CRBSI
What is differential time to positivity (DTP)? How can it be used to diagnose CRBSI?
- DTP is the time between the through line sample becoming positive and peripheral sample becoming positive
- 1) take peripheral culture from peripheral vein
- 2) take blood culture from line
- If DTP >2 hours (i.e. if through line culture becomes positive >2 hours before peripheral culture) then this is highly suggestive of CRBSI
What is infective endocarditis?
Infection of the endocardium or devices within the heart
What is the pathological lesion in infective endocarditis?
Vegetation;
- Infection of the endocardium or devices within the heart
- Wrapped in fibrin, attached usually to heart valve
What type of bacteraemia (based on timing) is infective endocarditis? How would blood cultures demonstrate this?
Every blood sample should be positive for bacteraemia as this is chronic/continuous
What are the 3 major types of presentation of infective endocarditis?
- 1) Non-specific illness (lethargy, malaise, night sweats, anorexia, weight loss)
- 2) Heart failure (SOB, orthopnea, PND)
- 3) Results of extra-cardiac foci of infection (back pain from HVO, stroke, abdominal pain from splenic infarct
When should you be highly suspicious of infective endocarditis?
Particularly if known heart valve disease, pacemaker, prosthetic valve, congenital heart disease
