Week 2 Lab: Screening Test for Phagocytic Engulfment Flashcards
True or False: No special preparation of the patient is required before specimen collection.
True
Blood should be drawn by an _____ technique.
aseptic
Blood sample: A minimum of ______________ or ______________ are required.
- 2 mL of heparin blood (green-top evacuated tube)
- 15 to 20 heparinized capillary tubes
After blood collection, the specimen should be _________.
centrifuged
For the quality control, _________________ should be tested simultaneously.
a fresh, heparinized sample of blood from a healthy volunteer
Materials for the experiment?
• Broth culture of Bacillus subtilis or Staphylococcus epidermidis
• Microscope slides
• Pasteur pipettes
• Rubber bulb
• Test tubes
• Wright’s stain
What are the labels of the 2 test tubes?
Patient test tube and Control test tube
Add ______ drops of the buffer coat from either blood sample to the respectively labeled tubes.
4 to 8 drops
Add ______ drops of the bacterial broth culture to each tube.
2 to 3 drops
Incubate both tubes at room temperature or _____ for _____.
37C; 30 minutes
Place _____of the incubated specimen on a glass slide and prepare a smear.
1 drop
Air dry the slides and stain with _________.
Wright’s stain
Cover each smear generously with filtered Wright’s stain and allow the stain to remain on the slide for at least _________.
5 minutes
Slowly add distilled water or buffer to the stain until the buffer begins to overflow the stain. Watch for the appearance of a _________.
metallic luster
Gently _____ on the slide to mix the stain and buffer.
blow
Allow the buffer to remain on the slide for at least _________.
5 minutes
Gently wash the stain and buffer off the slide with ___________.
distilled water
Air dry or carefully blot the slide between two sheets of ___________.
bibulous paper
Interpretation of Results: Positive?
Demonstration of the engulfment of bacteria
Interpretation of Results: Negative?
No engulfment of bacteria
It is the process by which specialized cells engulf and destroy foreign particles such as microorganisms or damaged cells.
Phagocytosis
___________ are the most important phagocytic cells.
Macrophages and neutrophils (PMNs)
A mixture of bacteria and phagocytes is incubated and examined for the presence of engulfed bacteria. This simple procedure may be useful in supporting the diagnosis of ___________________ in conjunction with clinical signs and symptoms.
impaired neutrophilic function
This procedure may produce ____________ if the blood specimen is not fresh or if a coagulase-positive Staphylococcus specimen is used.
false-negative results
This procedure may produce false-negative results if _______________.
- the blood specimen is not fresh
- if a coagulase-positive Staphylococcus specimen is used
In Addition, the bacteria must be ___________ for the test to be positive.
intracellular and not extracellular
The failure of phagocytes to engulf bacteria can support the diagnosis of __________; however, these results must be used in conjunction with patient signs and symptoms.
neutrophilic dysfunction
True or False: This is the simple screening procedure for engulfment. The presence of engulf bacteria does not demonstrate that the bacteria have been destroyed.
True
