Deck 31: Diagnostic Microbiology and Immunology

Question 1

Latex bead agglutination tests are

A) inferior tests used in developing countries not having facilities for more reliable assays.
B) an integral part of the EIA test procedure.
C) too expensive for routine use.
D) rapid and reliable tests used for the detection of certain bacteria as well as certain serum antibodies.

Answer 1

D

Question 2

The component that enriches chocolate agar is

A) methyl brown indicator dye.
B) chocolate.
C) heat- lysed blood cells.
D) none of these.

Answer 2

C

Question 3

Detection of antibody in the serum is sufficient to indicate infection in diseases

A) caused by pathogens commonly found in a population.
B) caused by pathogens rarely found in a population.
C) that are caused by viruses.
D) that are acute.

Answer 3

B

Question 4

The most common of all nosocomial infections are infections.

A) urinary tract
B) reproductive tract
C) respiratory tract
D) blood

Question 5

Immunoblot tests for HIV screening are NOT likely to supplant the EIA screening method, because

A) they are more labor intensive than EIA.
B) they are more time consuming to perform than EIA.
C) they are more costly than EIA.
D) of all of the above.

Question 6

Blood agar is an example of a(n) medium.

A) selective
B) enrichment
C) differential
D) general- purpose

Question 7

Which component of HAT medium is a cell poison that blocks metabolism?

A) aminopterin
B) thymidine
C) hypoxanthine
D) none of the above

Question 8

EMB agar preferentially selects for the growth of bacteria.

A) gram- negative
B) gram- variable
C) gram- positive
D) all of the above

Question 9

Chocolate agar is an example of a _ medium.

A) general- purpose
B) differential
C) selective
D) nonselective enriched

Question 10

Which bacterium shows a characteristic green sheen when grown on eosin- methylene blue (EM.B agar?

A) Streptococcus pyogenes
B) Salmonella enterica
C) Staphylococcus aureus
D) Escherichia coli

Question 11

Which of the following immunological tests would allow the specific identification of a microorganism directly in a patient specimen?

A) radioimmunoassay (RIA)
B) agglutination
C) enzyme- linked immunosorbent assay (EIA)
D) fluorescent antibody (FA)

Question 12

A laboratory in which Ebola virus is studied would be classified as a BSL- laboratory.

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

Question 13

The disk- diffusion test is used for

A) minimum inhibitory concentration (MIC) determinations.
B) assessing antimicrobial activity.
C) serial dilution measurements.
D) all of the above.

Question 14

Intestinal parasites can be identified by observing stool samples for the presence of

A) LPS.
B) antibodies.
C) blood.
D) cysts.

Question 15

MacConkey agar and eosin- methylene blue (EMB) agar are _ media.

A) differential but not selective
B) selective but not differential
C) both selective and differential
D) neither selective nor differential

Question 16

Which organism can be detected in either humans or foods by nucleic acid probes?

A) Chlamydia trachomatis
B) Staphylococcus aureus
C) Neisseria gonorrhoeae
D) all of the above

Question 17

Which type of medium typically contains an indicator dye?

A) differential but not selective
B) selective but not differential
C) both selective and differential
D) neither selective nor differential

Question 18

Protein A, commonly used in immunoblots, is derived from

A) Escherichia.
B) Bacillus.
C) Staphylococcus.
D) Clostridium.

Question 19

Antibody titer can be measured by

A) plate counts done after isolating the pathogen.
B) agglutination.
C) negative microscopy.
D) none of the above.

Question 20

The oxygen- free gas commonly employed during anoxic incubation of a bacterial culture is a mixture of

A) nitrogen and carbon monoxide.
B) nitrogen and hydrogen.
C) nitrogen and argon.
D) nitrogen and carbon dioxide.

Question 21

The MIC procedure involves dilution assay(s).

A) an antibiotic
B) a culture
C) antibiotic and culture
D) neither antibiotic nor culture

Question 22

The dipstick nitrite test is a very rapid check for urinary tract infections because

A) nitrite is reduced to nitrate in the presence of urine.
B) only pathogenic bacteria produce nitrite.
C) significant nitrite production is apparent only when large numbers of enteric bacteria are present.
D) of all of the above.

Question 23

The blotting of proteins from polyacrylamide gels to nitrocellulose paper, and the subsequent identification by specific antibodies, is called a(n) blot.

A) Southern
B) Northern
C) Eastern
D) Western

Question 24

An Etest® is a clinical tool used for the determination of

A) the minimum inhibitory concentration (MIC) value of an antimicrobial agent.
B) enteric presence.
C) pathogenic enzyme activity.
D) Escherichia coli O157:H7 presence.

Question 25

A gram- negative, oxidase- positive diplococcus growing on chocolate agar likely belongs to the genus .

Question 26

The study of antigen- antibody reactions, which is the interaction of antigenic determinants
with the _ region of the antibody molecule, is known as _.

Question 27

Two pathogenic anaerobes that are predominantly soil organisms are Clostridium
and C. .

Question 28

Bacteremia is a term used

A) when the same organism is isolated from more than one site.
B) to indicate the presence of bacteria in the blood.
C) synonymously with septicemia.
D) in all of the above circumstances.

Question 29

Hybridization requires a nucleic acid that binds to DNA or RNA of interest, which must be in the _ form for hybridization to occur.

Question 30

One advantage of the fluorescent antibodies that permits disease diagnosis long before primary isolation techniques yield results is that

A) few controls are required.
B) cross- reactions do not occur.
C) it may be applied directly to tissue.
D) nonspecific staining does not occur.

Question 31

Common contaminants in blood drawn from a vein include all EXCEPT which of the following?

A) Escherichia coli
B) Propionibacteria
C) Coryneform bacteria
D) Staphylococcus epidermidis

Question 32

Factors rendering EIA a useful immunodiagnostic tool include

A) sensitivity.
B) long shelf life.
C) speed.
D) all of the above.

Question 33

, periodic reports on the susceptibility of clinically isolated organisms to the antibiotics in current local use, are particularly valuable for tracking the emergence of new antibiotic- resistant strains of pathogens.

Question 34

Compared with other precipitation tests, agglutination tests are

A) less sensitive.
B) more sensitive.
C) highly variable in sensitivity, and thus the sensitivities cannot be compared.
D) about equally sensitive.

Question 35

In attempting to isolate a specimen from a disease site, recovery or detection may not be possible because of

A) failure to meet the metabolic needs of the purported pathogen.
B) an insufficient inoculum.
C) failure to ensure aseptic conditions.
D) all of the above.

Question 36

The tuberculin skin test looks to identify _ specific to Mycobacterium tuberculosis.

A) delayed hypersensitive (DTH) TH1 cells
B) delayed hypersensitive (DTH) TC cells
C) antibodies
D) antigens

Question 37

To perform a precipitation reaction, both the antigen and antibody must be

A) insoluble.
B) bivalent.
C) soluble.
D) in vivo.

Question 38

Which of the following must be available when using a nucleic acid probe to identify a specific clinical microorganism?

A) a reporter molecule
B) partially denatured DNA from alkali- lysed cells
C) a single strand of DNA with a sequence unique to the gene of interest
D) all of the above

Question 39

Modified Thayer- Martin (MTM) agar

A) permits the growth of Neisseria gonorrhoeae and Neisseria meningitidis.
B) incorporates antibiotics into the medium.
C) suppresses the growth of normal flora.
D) does all of the above.

Question 40

The basis for blood typing is referred to as

A) precipitation.
B) immunodiffusion.
C) neutralization.
D) hemagglutination.

Question 41

In the United States, every clinical and research institution requires that workers be protected from and _, both of which are contracted almost exclusively from handling patient specimens (rather than from known exposure or accidents).

Question 42

Name two common or important bacterial pathogens found in each of the following locations below.
A. Blood: _ _ and _
B. Urinary tract: _ _ and _
C. Fecal area: _ and
D. Wound: _ and
E. Reproductive tract: _ and

Question 43

is a molecular method that involves digesting SSU rRNA genes with restriction endonucleases to identify particular species, even strains of interest.

Question 44

SYBR Green, commonly used in the method, binds nonspecifically to but not or .

Question 45

use genotypic rather than phenotypic factors to identify specific pathogens.

Question 46

Nucleic acid probes are not suitable for the detection of viruses.

Question 47

Identification of the agents of infection can be made long before primary isolation methods yield a suspected organism when tissues are probed with specific fluorescent antibodies.

Question 48

In most cases, urinary tract infection occurs because of .

Question 49

The direct EIA is used to detect , whereas the indirect EIA is used to detect
.

Question 50

The PCR application that is frequently used in clinical diagnostic laboratories to determine cell concentration is _.

Question 51

The use of selected culture media and incubation conditions to isolate microorganisms from samples is known as a(n) _ .

Question 52

defines the lowest quantity of an antigen that can be detected in a serological test.

Question 53

Most microbiology research laboratories maintain BSL- 2 standards.

Question 54

Obligately anaerobic normal flora are found in and _ _, which are anoxic habitats in the body.

Question 55

Protein A has a strong affinity for .

Question 56

Two important intestinal pathogens generally acquired from contaminated food or water are and .

Question 57

Two- component probes function as both a(n) and a(n) .

Question 58

The most specific antibodies are .

Question 59

Literally hundreds of clinically useful EIAs have been developed.

Question 60

One problem with the EIA test is the disposal of radioactive wastes.

Question 61

All positive HIV- EIA tests must be confirmed by another independent test, usually the HIV Western blot.

Question 62

Advanced cases of AIDS may not give a positive EIA test.

Question 63

When using the EIA test for HIV screening, both false negative and false positive results are possible.

Question 64

Urinary tract diseases are more common among females than they are in males.

Question 65

To detect antibodies in human serum, the direct EIA is most commonly employed.

Question 66

Fluorescent antibodies can be used to separate mixtures of cells into relatively pure populations with a fluorescence cytometer.

Question 67

At this time, EIA tests are too difficult for routine diagnoses.

Question 68

In the EIA test for HIV infection, the microtiter plate is coated with disrupted HIV particles.

Question 69

The EIA test for HIV infection is a direct test for HIV envelope proteins.

Question 70

One of the problems encountered when using fluorescent and radioisotopically labeled monoclonal antibodies is the tedious culturing procedures that must be used.

Question 71

In cases of suspected foodborne or waterborne infections, fecal samples should be inoculated into a variety of selective media.

Question 72

Discuss how recent advances in the molecular biology of nucleic acids have revolutionized methods used for the identification of infectious disease agents and how they are favored over traditional biochemical tests.

Question 73

Finding no bacterial growth, despite persistent urinary tract symptoms, indicates that the problem is likely either nonpathogenically physiological or psychosomatic.

Question 74

Obligate anaerobic bacteria are often missed as the causal agents of infection in clinical diagnosis. Why is this so? Describe one method commonly used to culture these bacteria.

Question 75

Antibodies and antigens can be reported in mass units called antibiograms.

Question 76

What is the basis for inferring infection of a pathogen when a serological EIA is performed? In this context, what does a positive result indicate?

Question 77

Nucleic acid probes and immunological reagents are not commonly used in the clinical laboratory for the diagnosis of viral disease, because the cultivation of the virus is often difficult or even impossible.

Question 78

Hydrogen sulfide production is assayed by growth in a medium containing ferric iron (Fe3+).

Question 79

The causal agents of urinary tract diseases are often members of the normal flora.

Question 80

Some infectious agents, such as Neisseria gonorrhoeae, do not elicit a systemic immune response.