Ch 17

Question 1

What is sensitivity?

Answer 1

• 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

Question 2

Know the process for agglutination tests

Answer 2

.

Question 3

Know the process for precipitation tests

Answer 3

.

Question 4

When serotyping a bacteria, what kind of bacterial traits are identified?

Answer 4

.

Question 5

What is required for a direct immunofluorescence test?

Answer 5

.

Question 6

What is serum titer?

Answer 6

The highest dilution of serum that still produces agglutination

Question 7

How is titer related to infection or infectious agent?

Answer 7

.

Question 8

How does the Western blot test work?

Answer 8

• 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

Question 9

What does the Western blot test test for and when is it used?

Answer 9

Microbial-specific antigens in patient samples; used as a verification test for HIV screening tests

Question 10

What are phenotypic methods of identification?

Answer 10

Isolation media (Differential media/Blood cultures), Biochemical Testing, and Miscellaneous Tests (Phage Typing/Antimicrobial sensitivity test)

Question 11

What are examples of biochemical tests?

Answer 11

• Carbohydrate fermentation: production of acid and/or gas
• Hydrolysis of gelatin, starch, and other polymers
• Actions of enzymes: catalase, oxidase, coagulate

Question 12

What are the advantages of genotype methods of identification?

Answer 12

Get results in 3 hours rather than weeks

Question 13

Know about specimens collection. Where collected, how collected, media required, etc.

Answer 13

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Question 14

Know about the tuberculosis serological test.

Answer 14

• 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

Question 15

What is required for antibody testing?

Answer 15

***The corresponding antigen

Question 16

What does serological testing rely upon to be effective?

Answer 16

**The presence of either an antibody or antigen.

Question 17

What is specificity?

Answer 17

• 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