Deck 7: Immunologic Detection of Infectious Diseases

Question 1

Which technique below describes Ouchterlony double diffusion?

A)Antibodies are added to liquid agarose, and the agarose is allowed to harden. Holes are cut in agarose, and specimens are placed in the holes. The specimens diffuse out of their wells, forming precipitin rings.
B)Antibodies are added to liquid agarose, and the agarose is allowed to harden. Holes are cut in agarose, and specimens are placed in the holes. The agarose is placed in an electrical field, and the specimens migrate out of their wells, forming precipitin lines.
C)Holes are cut in agarose. Antibodies are placed in one well, and a specimen is placed in the other well. The agarose is placed in an electrical field, and the antibodies and specimen migrate out of their wells, meeting in the middle, forming a precipitin line.
D)Holes are cut in agarose. Antibodies are placed in one well, and a specimen is placed in the other well. The antibodies and specimen diffuse out of their wells, meeting in the middle, forming a precipitin line.

Answer 1

Holes are cut in agarose. Antibodies are placed in one well, and a specimen is placed in the other well. The antibodies and specimen diffuse out of their wells, meeting in the middle, forming a precipitin line.

Question 2

Rapid immunoassays for the detection of antibiotic- associated pseudomembranous colitis agent(s)in stool samples detect

A)Escherichia coli verotoxin (shiga- like toxin).
B)Campylobacter group antigen.
C)Clostridium difficile toxins A and B.
D)All of the above.

Answer 2

Clostridium difficile toxins A and B.

Question 3

Which hepatitis virus(s)below is (are)transmitted by the fecal/oral route?

A)Hepatitis D (delta agent)virus
B)Hepatitis A virus
C)Hepatitis B virus
D)Hepatitis C virus
E)All of the above

Answer 3

Hepatitis A virus

Question 4

All of the following are members of Herpesviridae except

A)hantavirus.
B)Epstein Barr virus.
C)cytomegalovirus.
D)varicella zoster virus.
E)herpes simplex 1.

Question 5

Rapid immunological assays for Group A Streptococcus pyogenes antigen have a sensitivity of about 60% to 80% and a specificity of about 90% to 95% in pharyngitis infections. Given these data, which strategy below is optimal?

A)Do preliminary screening with a throat culture and follow up negative results with a rapid antigen test.
B)Do preliminary screening with a rapid antigen test and follow up negative results with a throat culture.
C)Do preliminary screening with a rapid antigen test and follow up positive results with a throat culture.
D)Do preliminary screening with a throat culture and follow up positive results with a rapid antigen test.
E)Simultaneously test all specimens with both rapid antigen screening and culture.

Question 6

In the normal course of a hepatitis B virus infection, what is the order of appearance of the following markers in serum? 1. Hepatitis B surface antigen
2) Hepatitis B early antigen
3) Anti- hepatitis B surface antigen
4) Anti- hepatitis B early antigen
5) Anti- hepatitis B core antigen

A)1, 2, 3, 4, 5
B)1, 2, 5, 4, 3
C)2, 1, 4, 3, 5
D)2, 1, 3, 4, 5

Question 7

Which of the following non- treponemal tests must be read using a microscope?

A)Toluidine red unheated serum test (TRUST)
B)Venereal Disease Research Laboratory (VDRL)
C)RST- reagin screen
D)Rapid plasma reagin (RPR)
E)All of the above

Question 8

An important agent of childhood gastroenteritis that can be identified by extracting viral antigen from stool samples and reacting it with corresponding antibody is

A)rotavirus.
B)norovirus.
C)coronavirus.
D)adenovirus.
E)calcivirus.

Question 9

How can soluble antigens with multiple epitopes be mixed with antibodies and have visible agglutination occur?

A)Attach the antibodies to killed Staphylococcus aureus cells.
B)Attach the antibodies to liposomes.
C)Attach the antibodies to latex particles.
D)All of the above.

Question 10

Bacterial antigens associated with a meningitis infection can be detected using rapid immunoassays in which of the following?

A)Cerebrospinal fluid
B)Urine
C)Serum
D)All of the above

Question 11

What advantage does countercurrent immunoelectrophoresis have over Ouchterlony double diffusion?

A)It requires a smaller specimen volume.
B)It is faster.
C)It requires less instrumentation.
D)Complement does not interfere with the procedure.

Question 12

In general, rapid immunoassays for Legionella pneumophilia have the highest sensitivities and specificities when the specimen tested is

A)serum or plasma.
B)whole blood.
C)urine.
D)a deep cough sputum.
E)a nasopharyngeal swab.

Question 13

A patient is covered by a rash over most of his body, including the palms of the hands and soles of the feet. He also has lymphadenopathy, fatigue, and fever. His RPR is positive with a titer of 1:1024, and his FTA- Abs is positive. This description is most consistent with

A)primary syphilis.
B)latent syphilis.
C)tertiary syphilis.
D)biological false positive test for syphilis.
E)secondary syphilis.

Question 14

A positive test for the presence of antibodies in a complement fixation test is

A)lysis of red blood cells.
B)no lysis of red blood cells.
C)precipitation of antigen/antibody complexes.
D)no precipitation of antigen/antibody complexes.

Question 15

Which characteristic(s)below do herpes viruses share?

A)Generally only cause clinical symptoms in immunocompromised patients.
B)Active infections that become latent, potentially reactivating many years later.
C)Virtually impossible to grow in artificial cell culture.
D)Poor antibody response to infection and generally insensitive serologic testing.
E)All of the above.

Question 16

A cerebrospinal specimen was cultured for bacterial microbes and tested for specific bacterial antigens by latex agglutination. The latex agglutination was positive for Neisseria meningitidis antigen but no organisms grew from the culture. Which of the following could best explain this?

A)The specimen only contained nonviable organisms.
B)The specimen was filtered prior to bacterial antigen testing.
C)The specimen was centrifuged prior to bacterial antigen testing.
D)The specimen was heated prior to bacterial antigen testing.
E)All of the above.

Question 17

A latex agglutination test is done for Legionella antigen. Reactions were as follows: latex particles coated with murine anti- Legionella + specimen = 2+ agglutination
Latex particles coated with murine anti- Legionella + positive control = 2+ agglutination latex particles coated with murine anti- Legionella + negative control = no agglutination latex particles coated with non- specific murine antibodies + specimen = 2+ agglutination
What is the best interpretation of this set of data?

A)This specimen may have heterophile antibodies or other cross- reacting species and should be tested by another method.
B)The specimen is negative for Legionella antigen.
C)The assay must be repeated because the positive and negative controls appear to have been mixed up.
D)The specimen is positive for Legionella antigen.

Question 18

Each test below can be used as a confirmatory test for syphilis because it uses Treponema pallidum antigen to detect specific syphilis antibodies except

A)fluorescent treponemal antibody absorption (FTA- Abs).
B)Venereal Disease Research Lab (VDRL).
C)microhemagglutination Treponema pallidum (MHA- TP).
D)Treponema pallidum immobilization (TPI).
E)fluorescent treponemal antibody absorption double stained (FTA- Abs DS).

Question 19

What is (are)the advantage(s)of using monoclonal antibodies to detect microbial antigens in a specimen?

A)Results may be positive for organisms difficult or impossible to grow.
B)Results may be positive before a culture has time to grow.
C)Results may be positive before the subject has developed detectable antibodies.
D)Results may be positive when the organism in the specimen has died due to poor handling.
E)All of the above.

Question 20

In which situation below is rapid bacterial antigen testing in a suspected case of meningitis the optimal course of action?

A)When the patient has already been stared on antibiotic therapy.
B)When the cerebrospinal fluid is visibly cloudy with red blood cells.
C)When the Gram stain of the cerebrospinal fluid is positive.
D)When the cerebrospinal fluid is visibly cloudy with white blood cells.
E)When the Gram stain of the cerebrospinal fluid is negative.

Question 21

An advantage of using Staphylococcus aureus cells for coagglutination instead of liposomes is that a colored dye can be incorporated into the Staphylococcus aureus enhancing visualization of the agglutination.

Question 22

Which term below refers to doing testing to prove that the claims in the manufacturer's literature about a test are accurate?

A)Documentation
B)Verification
C)Confirmation
D)Substantiation
E)Validation

Question 23

Adults tend to have a poorer heterophile antibody response in infectious mononucleosis than children.

Question 24

Precision refers to how closely a test result comes to the true value.

Question 25

In order to verify the claims in manufacturer's literature of an FDA- approved procedure, at least specimens should be done that contain the analyte and specimens that do not.

A)100, 100
B)20, 20
C)50, 50
D)20, 50
E)50, 100

Question 26

What does the formula below calculate? Number of true positive results _{x 100} Number of true positive results + false negative results
Where true positive results are patients with a disease who test positive and false negatives are patie with a disease who test negative

A)Clinical sensitivity
B)Clinical specificity
C)Accuracy
D)Precision

Question 27

Arboviruses are transmitted by the fecal/oral route and are important causes of gastroenteritis.

Question 28

The major serotype of HIV in the United States is HIV- 1.

Question 29

Even after syphilis is cured, nontreponemal antibodies may persist for a lifetime, but once the disease is no longer active, specific treponemal antibody titers decrease to undetectable levels.

Question 30

What laboratory regulation established testing requirements by categorizing laboratory tests as waived, moderately complex, or highly complex?

A)National Consensus for Clinical Laboratory Standards (NCCLS)
B)Centers for Disease Control Testing Tiers Regulation
C)Clinical Laboratory Improvement Amendment of 1988 (CLIA)
D)College of American Pathologists (CAP)Cumitech #31

Question 31

The process in which certain chemicals emit light when they are electrically stimulated is
.

Question 32

A positive test for hepatitis C antibody can be confirmed by or _ .

Question 33

A chronic carrier of hepatitis B virus typically fails to develop the _ antibody and the antibody.

Question 34

Reactivation of cytomegalovirus infection is particularly problematic in patients.

Question 35

An advantage of using enzyme labeled antibodies instead of fluorochrome labeled antibodies is that the colors are more stable in storage.

Question 36

By law, laboratories may not use "home- brew" or non- FDA approved tests.

Question 37

Which of the agents below is particularly problematic in immunocompromised patients and causes both pneumonia and meningitis?

A)Cryptococcus neoformans
B)Cryptosporidium parvum
C)Pneumocystis carnii
D)Giardia lamblia

Question 38

Approximately 95% of all clinically significant intestinal parasites in the United States are either

Question 39

To increase assay sensitivity, instead of coupling enzyme labels directly to antigens or antibodies, _ and can be used intermediary molecules because they bind tightly to each other and amplify signal because of multiple binding sites.

Question 40

It is impossible to be infected with hepatitis D (delta agent)virus without simultaneously being infected with hepatitis B virus.

Question 41

Describe the technique of measuring acute and convalescent titers in an infection and how the titers can be used to make a diagnosis.

Question 42

Explain the properties of the Cowan 1 strain of Staphylococcus aureus that allow it to be a passive carrier of antibody in coagglutination procedures and how these properties contribute to an increased chance of false positive tests in some specimens.

Question 43

Describe how and why the heterophile antibody associated with infectious mononucleosis is identified.

Question 44

List the steps in an indirect solid phase immunosorbent assay for Hepatitis B surface antigen (HBsAg)using an enzyme labeled detection antibody.

Question 45

Discuss the testing strategies for detecting infection with human immunodeficiency virus (HIV).