Deck 27: Diagnostic Microbiology

Question 1

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

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

Answer 1

A

Question 2

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

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

Answer 2

C

Question 3

The most common of all nosocomial infections are ________ infections.

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

Answer 3

C

Question 4

Laboratories that work with moderate risk pathogens are classified as

A)BSL-1.
B)BSL-2.
C)BSL-3.
D)BSL-4.

Question 5

The component that enriches chocolate agar is

A)chocolate.
B)methyl brown indicator dye.
C)heat-lysed blood cells.
D)None of the answers are correct.

Question 6

Latex bead agglutination tests are

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

Question 7

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

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

Question 8

EMB agar preferentially selects for the growth of ________ bacteria.

A)gram-positive
B)gram-negative
C)gram-variable
D)both gram-positive and gram-negative

Question 9

Which of the following must be accomplished FIRST in order to conduct RT-PCR?

A)Complementary DNA must be synthesized from double-stranded DNA.
B)Complementary DNA must be synthesized from RNA.
C)Complementary DNA must be synthesized from proteins.
D)Complementary DNA must be synthesized from single-stranded DNA.

Question 10

Which of the following is a mechanism of aminoglycosides?

A)inhibition of cell wall biosynthesis
B)prevention of peptidoglycan crosslinking
C)inhibition of DNA replication
D)targeting the 30S ribosomal subunit

Question 11

The first antibiotic to be characterized was a

A)cephalosporin.
B)quinolone.
C)β-lactam.
D)macrolide.

Question 12

Some antibiotics inhibit protein synthesis by disruption of translation through interactions with the

A)ribosome.
B)protein.
C)DNA.
D)chromosome.

Question 13

The disk-diffusion test is used for

A)assessing antimicrobial activity.
B)the identification of Escherichia coli.
C)the identification of viral plaques.
D)the detection of antigen.

Question 14

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

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

Question 15

Modified Thayer-Martin (MTM)agar

A)incorporates antibiotics into the medium.
B)enhances the growth of normal flora.
C)prevents the growth of Neisseria gonorrhoeae,but promotes the growth of Neisseria meningitidis.
D)prevents the growth of Neisseria meningitides,but promotes the growth of Neisseria gonorrhoeae.

Question 16

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

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

Question 17

Bacteremia is a term used

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

Question 18

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

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

Question 19

Which type of medium typically contains an indicator dye?

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

Question 20

Which of the following would be useful for treating Candida?

A)an azole
B)a fusion inhibitor
C)a macrolide
D)a nucleoside reverse transcriptase inhibitor

Question 21

Widespread antimicrobial drug resistance is usually passed by

A)heterologous gene expression.
B)reverse transcription.
C)horizontal gene transfer.
D)gene splicing.

Question 22

Compared with other precipitation tests,agglutination tests are

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

Question 23

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

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

Question 24

Which bacterium shows a characteristic green sheen when grown on eosin-methylene blue (EMB)agar?

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

Question 25

Antibody titer can be measured by

A)negative microscopy.
B)agglutination.
C)plate counts done after isolating the pathogen.
D)polymerase chain reaction.

Question 26

Protein A,commonly used in immunoblots,is derived from

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

Question 27

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

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

Question 28

Two common or important bacterial pathogens found in the blood are

A)Pseudomonas aeruginosa and Escherichia coli.
B)Enterobacter and Proteus.
C)Shigella and Salmonella.
D)HIV and Escherichia coli.

Question 29

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

A)Neisseria.
B)Escherichia.
C)Mycobacterium.
D)Pseudomonas.

Question 30

________,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.

A)Antibiotic susceptibility plates
B)Antibiograms
C)Direct agglutination reports
D)Histograms

Question 31

Which of the following prevents supercoiling of bacterial DNA?

A)macrolides
B)quinolones
C)penicillins
D)cephalosporins

Question 32

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

A)Specificity
B)Antigenic capacity
C)Minimal inhibitory concentration
D)Sensitivity

Question 33

Most drug-resistant bacteria isolated from patients contain a(n)

A)R plasmid.
B)T1 phage.
C)reverse transcriptase.
D)β-lactam.

Question 34

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

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

Question 35

Chocolate agar is an example of a ________ medium.

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

Question 36

Which of the following is a cause of drug-specific resistance in disease-causing organisms?

A)inappropriate hygiene
B)nosocomial infection
C)poor immunity
D)indiscriminate nonmedical use of antimicrobials

Question 37

Which of the following is a novel antimicrobial target?

A)disruption of lipid biosynthesis
B)inhibition of protein synthesis
C)inhibition of cell wall biosynthesis
D)inhibition of peptidoglycan crosslinking

Question 38

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

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

Question 39

The basis for blood typing is referred to as

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

Question 40

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

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

Question 41

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

Question 42

Indirect EIA is used to detect

A)antigens.
B)antibodies.
C)viruses.
D)serum.

Question 43

SYBR Green,commonly used in qPCR,binds nonspecifically to

A)ssDNA
B)dsDNA
C)ssRNA
D)dsRNA

Question 44

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

Question 45

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

A)differential culture.
B)selective culture.
C)enrichment culture.
D)sensitive culture.

Question 46

Protein A has a strong affinity for

A)antigen.
B)blood.
C)protein.
D)antibody.

Question 47

Obligately anaerobic normal flora are found in ________,which is an/are anoxic habitat(s)of the body.

A)the kidneys
B)the skin
C)portions of the oral cavity
D)the lungs

Question 48

Methylene blue in EMB agar is selective for

A)gram-positives.
B)gram-negatives.
C)viral plaques.
D)both gram-positives and gram-negatives.

Question 49

How is drug-resistant Neisseria gonorrhoeae treated?

A)with penicillinase-resistant β-lactams
B)with tetracycline
C)with synthetic analogs of tetracycline
D)with vancomycin

Question 50

The study of antigen-antibody reactions is known as

A)serology.
B)immunology.
C)toxicology.
D)epidemiology.

Question 51

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

Question 52

Which of the following antibiotics inhibits RNA synthesis?

A)penicillin
B)erythromycin
C)rifampin
D)azithromycin

Question 53

An important intestinal pathogen generally acquired from contaminated food or water is

A)Clostridium perfringens.
B)Mycobacterium tuberculosis.
C)Ebola virus.
D)Escherichia coli O157:H7.

Question 54

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

A)single-stranded
B)double-stranded
C)oligomerized
D)polymerized

Question 55

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

Question 56

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

Question 57

A mechanism for penicillin resistance in bacteria is

A)acetylation of the antibiotic.
B)phosphorylation of the antibiotic.
C)confirmation change of the antibiotic.
D)splitting the β-lactam ring of the antibiotic.

Question 58

________ is used to monitor gene expression of a pathogen.

A)Reverse transcription PCR
B)Serology
C)Antigen capture assay
D)Qualitative PCR

Question 59

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

A)anthrax
B)hepatitis B
C)drug-resistant mycobacteria
D)influenza

Question 60

A positive antibody titer indicates

A)previous exposure to an antigen.
B)active infection.
C)latent disease.
D)a healthy individual.

Question 61

Describe the use of combination drugs and why they are effective.Provide examples.

Question 62

Chitin is found ONLY in fungi and insects.

Question 63

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

Question 64

Many pathogens can be readily grown in laboratory culture.

Question 65

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

Question 66

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

Question 67

Salmonella is commonly associated with wound infections.

Question 68

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

Question 69

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

Question 70

Describe the three main components to PCR-based testing.

Question 71

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

Question 72

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 73

Use specific examples to describe the difference between a differential and a selective medium.

Question 74

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

Question 75

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

Question 76

Gram stain smears of urethral exudates for the detection of Neisseria gonorrhoeae are highly specific.

Question 77

Interferons promote viral replication.

Question 78

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

Question 79

Literally hundreds of clinically useful EIAs have been developed.

Question 80

MOST microbiology research laboratories maintain BSL-2 standards.