Glossary of Hematologic and Vascular infections

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What are 2 characteristics of Bacteremia?
-Secondary to infection elsewhere.
What are 2 characteristics of Septicemia?
-Bloodstream infection
-Usually systemic spread of GNB.
What are the 2 types of Endocarditis?
What is the difference?
Subacute: less severe, caused by valve damage.
Acute: more severe, caused by primary infection.
What are the top two causes of bloodstream infections?
1. Coag neg staphs
2. Enterococcus
(check on this though)
How do Iv catheters cause BSIs?
-By causing biofilms
-NF on skin enters puncture site.
How are catheter-induced BSIs processed?
1. Cut off 2" of IV/catheter
2. Roll across BA w/ sterile forceps
How is a catheter roll interpreted?
If 15 or more colonies grew, indicates infection.
What timeframe should blood be collected in for:
Septic - doesn't matter.
Bacteremia - 30-45 min before fever spike.
What variables should be controlled during blood collection?
1. Skin antisepsis/venipuncture
2. Blood volume required
3. Number of draws/timing
4. NEVER draw from IV.
How many draws are optimal?
3 - 99% recovery

2 - 90%

1 - 80%
How soon before one arm can have another sample drawn?
45 minutes
What is the best wipe to use for cleaning the draw site?
Tincture of iodine
Describe the skin antisepsis prep:
1. Use alcohol wipe/iodine tinct
2. wipe 30-60 seconds
3. Wait 30 sec before puncture
What are the requirements re: blood volume for drawing?
Blood:diluent should be 1:10
How many mls per draw is optimal?
At least 20 mL
What should be done, whatever culture media is used for blood?
Vent at least one bottle for aerobic bugs.
What additive is used for blood cultures? What is its purpose?
SPS - anti coagulant to prevent clot from trapping bugs.
What bug resists SPS?
How long should blood cultures be incubated? At what temp?
Keep 5-7 days
37 'C
What are 4 Non-automated methods for blood cultures?
1. Manually observe the bottles
2. ISolator
3. Septi-Chek
4. Signal
How does the Isolator work?
-It spins the blood to concentrate bugs, then you inoculate the plate.
-Adds lysing reagent to free bugs from host cells.
How does the septi-chek work?
It has solid media in neck of tube, over broth. You invert everyday.
How does the Signal system work?
It detects CO2 released as bacteria grow. Forces gas into upper chamber above media.
What are the automated blood culture systems NOT for?
Identification; only detection.
What are the 4 principles of automated systems?
1. Fluorescence detection
2. Laser detection
3. Colorimetric CO2 detection
4. Headspace pressure change detection
-What's the principle of the Fluorescence detection?
-What's an example?
-Matrix at bottom of tube lets H+ ions release, changes fluorescence.
-Detector is against matrix.
-What's an example of the fluorescence detection?
Bactec 9000
What is a laser detection system?
Bactec LX
How does the laser detection work?
Growth of bacteria causes CO2 diffusion; Fluorescence changes; Laser passes through bottle neck and detects change.
How does the Colorimetric CO2 detection work?
Acidic CO2 causes a pH change in the environment, An indicator in matrix changes color.
What is an example of colorimetric detection?
What's another name for headspace pressue change detection? What does it work for?
-Works for ANY gas, not only CO2
-Decreases when bug USES O2
-Increases when bug produces gas.
How are positive blood cultures PROCESSED?
-Stain with 1)GRAM 2)ACRIDINE Orange
-Contact DOctor IMmediately!!!
-Culture to BA/Chocolate, if GNB do Lemb/MAC
What is the ACCEPTABLE CONTAMINATION RATE for blood cultures?
Less than 3%
What are some causes of blood culture contamination?
-Poorly trained phlebotomist
-Not drawing directly into tubes
-Poor skin prep
-Touched the site of puncture
-Drawing from the IV TUBE! :(
Bad contamination tracking
What are 4 indicators of bacterial contamination?
1. Only one bottle/3 is positive
2. Patient's WBC cnt is normal
3. 2/more organisms grow
4. Growth is slow to emerge.
How should a possibly contaminated transfusion blood bag be worked up?
1. Process as a blood culture
2. Inoculate 2 bottles
-25'C for psychrophiles
-37'C for mesophiles
3. Save bag/tube till done.

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