Lecture 11- Bacteremias Flashcards
Week 6
What are bacteremias?
Blood stream infections
Define bacteremia, specifically
Defined as the presence of bacteria in the blood stream
In a bacteremia, which must there be- fever or symptoms?
Either. But it is always defined by whether or not there is bacteria in the blood stream
What is sepsis?
A clinical syndrome with a set of criteria that have to be met, the leaking of blood vessels (leaking of bacteria) create organ dysfunction and then death
What criteria is used to define sepsis?
SIRS
How should sepsis be described?
A progressive disorder
Primary bacteremia compared to secondary bacteremia?
Primary: isolation of bacteria from the blood of an individual as the only source of said bacteria
Secondary: isolation of the bacteria from the blood as well as other sites
Transient bacteremia
Common, asymptomatic
Typically, not clinically important and usually only lasts a few minutes
What is intermittent bacteremia?
The most common type of significant bacteremia
Extravascular sources of infection that “spill” into blood
Repeating events and often
Continous bacteremia
Intravascular source of infection
Consistent presence of bacteria in the bloodstream
Is transient bacteremia a source of infection?
Typically no but it can be. Gaining access to the bloodstream is manner in which the bacteria COULD seed the tissue and start an infection. This leads to an increased risk for developing infectious endocarditis
Who is more at risk of developing endocarditis from transient bacteremia?
Patients with damaged valves and/or prosthetic valves
How is intermittent bacteria best described?
A repeating event. So, another organ may have an infection which then seeds into the bloodha
What types of infections can lead to intermittent bacteremia?
Pneumonia, UTI, abscess, GI perforation
What sources could lead to continuous bacteria?
Intravascular source of infection like an endocarditis or an intravascular line. Typically found with IV catheter related infections as they provide direct portal of entry to the body.
What are the most common types of continuous bacteremia?
Organisms that colonize the skin (staph aureus, staph epidermis, Candida albicans)
Remember, IV catheters are plastic, so they can develop biofilms
What type of test is used to diagnose bacteremia?
Lab testing with blood culture. Do this fast as early antibiotic therapy has a significant impact on disease outcome
How should the blood culture be collected?
Directly into bottle with culture media, send the sample to microbiology lab ASAP
Can you refrigerate blood culture bottles?
NO
What is the impact of rapid blood culture diagnosis on patient outcomes?
Less time in hospital or ICU
What are some issue surrounding blood culture diagnosis?
Skin prep, volume of blood taken, sites, number of bottles, timing, paediatric issues
Volume: what is the issue here?
Make sure large volume is collected. This way, even low levels of bacteremia can be detected
Describe SOP of blood culture collection volume, number of bottles
8-10ml per bottle
3-4 bottles (2 aerobic, 2 anaerobic)
THIS IS 32-40mL per patient
What volume of blood will detect 97% cases of bacteremia?
30-40ml
Describe SOP of timing of blood culture collection
Take before antibiotic initiation as bacteria must grow in the culture bottles
All (both) sets of cultures should be collected within the 24 hour window
Talk about SOP with BC collection with respect to the site
Site 1 then site 2 with 10-20 mins in-between
Blood culture issues with paediatric patients?
limit in volumes, use smaller bottles if less than 35lbs, collect 2 bottles with 1-3ml per bottle
This is ok as there is a higher rate of bacteria per volume so, need less blood for detection anyway
How can we tell if the line is the source of the infection?
Collect: peripheral blood cultures, need blood from LINE
If both correlate then need line tip, roll it on agar plate
find number of colonies
IF there are more than 15 colonies present on a line tip…
Colonized line
If there are fewer than 15 colonies on the line tip
There is a skin contaminant
When interpreting blood culture results, what are the two possibilities and what are we figuring out
If the bacteria that grew from blood culture is a real pathogen or a skin contaminant
Likely skin contaminant if…
Not generally a virulent organism, in only one bottle
Probably a pathogen if…
Same organism repeatedly at different times, more than one bottle and more than one set, a known virulent organism
