Ch 17 Flashcards
1
Q
What is sensitivity?
A
- the detection of even minute quantities of antibodies or antigens in a specimen
- reflects the degree to which a test will detect every positive person
2
Q
What is specificity?
A
- the property of a test to focus on only certain antibody or antigen
- does not react with unrelated or distantly related antigens
- the degree to which a test does not falsely detect who do not have a condition
3
Q
What is the process for agglutination tests?
A
- Antisera containing antibodies against the blood group antigens on red blood cells are mixed with a small sample of blood and read for the presence or a sense of clumping
- Used by blood banks to determine ABO and Rh (rhesus) blood types in preparation for transfusions
4
Q
What is the process for precipitation tests?
A
- The soluble antigen is precipitated (made insoluble) by an antibody
- antiserum has been carefully laid over an antigen solution
5
Q
When serotyping a bacteria, what kind of bacterial traits are identified?
A
.
6
Q
What is required for a direct immunofluorescence test?
A
Known antibodies
7
Q
What is serum titer?
A
- the concentration of antibodies in a sample
- determined by serially diluting patient serum into test tubes or wells of a microtiter plate
- defined by the highest dilution of serum that still produces agglutination
8
Q
How is titer related to infection or infectious agent?
A
.
9
Q
How does the western blot test work?
A
- A sample of proteins from a bacterial cell or virus is separated via electrical charge within a gel
- The proteins distributed throughout the gel are transferred and immobilized on a filter
- The filter is incubated with a patient’s serum containing antibody
- If the serum contains antibodies to the microbe, they will bind to the antigens on the filter paper
- A second antibody designed to see the Fc portion of a human antibody as an antigen is applied to the filter paper
- After incubation, sites of specific antigen-antibody binding appear as a pattern of bands that can be compare with positive and negative controls
10
Q
What does western blot test, test for and when is it used?
A
- Highly specific and sensitive way to identify or verify the presence of microbial-specific antigens in a patient sample
- used as a verification test for HIV screening tests
11
Q
What are phenotypic methods of identification?
A
- Isolation Media
- Differential media
- Blood cultures
- Biochemical Testing
- Miscellaneous Tests
- Phage typing
- Antimicrobial sensitivity tests
12
Q
What are examples of biochemical tests?
A
- Carbohydrate fermentation: production of acid and/or gas
- Hydrolysis of gelatin, starch, and other polymers
- Actions of enzymes: catalase, oxidase, coagulase
- Various by-products of metabolism
13
Q
What are the advantages of genotypic methods of identification?
A
Get results in 3 hours rather than weeks.
14
Q
Where is specimen collected?
A
.
15
Q
How is specimen collected?
A
.
