What is sensitivity?
- 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
Know the process for agglutination tests
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Know the process for precipitation tests
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When serotyping a bacteria, what kind of bacterial traits are identified?
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What is required for a direct immunofluorescence test?
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What is serum titer?
The highest dilution of serum that still produces agglutination
How is titer related to infection or infectious agent?
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How does the Western blot test work?
- A sample of proteins from a bacterial cell or virus is separated via electrical charge with 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 compared with positive and negative controls
What does the Western blot test test for and when is it used?
Microbial-specific antigens in patient samples; used as a verification test for HIV screening tests
What are phenotypic methods of identification?
Isolation media (Differential media/Blood cultures), Biochemical Testing, and Miscellaneous Tests (Phage Typing/Antimicrobial sensitivity test)
What are examples of biochemical tests?
- Carbohydrate fermentation: production of acid and/or gas
- Hydrolysis of gelatin, starch, and other polymers
- Actions of enzymes: catalase, oxidase, coagulate
What are the advantages of genotype methods of identification?
Get results in 3 hours rather than weeks
Know about specimens collection. Where collected, how collected, media required, etc.
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Know about the tuberculosis serological test.
- A small amount of purified protein derivative from Mycobacterium tuberculosis is injected into the skin
- The appearance of a red, raised, thickened lesion indicates exposure to tuberculosis
What is required for antibody testing?
***The corresponding antigen
What does serological testing rely upon to be effective?
**The presence of either an antibody or antigen.
What is specificity?
- the property of a test to focus on only a certain antibody or antigen
- does not react with unrelated or distantly related antigens
- the degree to which a test does not falsely detect people who do not have a condition
