Question 1

Which of the following best describes the primary advantage of genotypic methods over phenotypic methods for microbial identification?

Accepted Answer

Genotypic methods do not require culturing microorganisms, which is beneficial for identifying nonculturable pathogens.

Question 2

A patient presents with symptoms of sepsis. Why is it critical to use rapid identification methods rather than traditional culturing techniques?

Accepted Answer

Traditional culturing takes too long, increasing mortality risk, and rapid identification enables targeted therapy sooner.

Question 3

Which of the following is an example of a phenotypic method that does NOT require cultivation?

Accepted Answer

Direct microscopic examination of a stained specimen

Question 4

A nurse collects a sputum sample for microbial identification. Which of the following is most important to avoid during collection?

Accepted Answer

Contamination with normal microbiota

Question 5

Which type of media would you use to isolate a suspected pathogen from a fecal sample containing a diverse microbiota?

Accepted Answer

Selective media

Question 6

In a biochemical test, a microbe is cultured in a medium containing a specific substrate. If the microbe possesses the enzyme to metabolize the substrate, what result would you expect?

Accepted Answer

A color change indicating a positive result

Question 7

Which of the following statements about serological testing is correct?

Accepted Answer

Serological tests rely on the specificity of antibody-antigen interactions.

Question 8

Which immunological diagnostic technique uses a secondary antibody labeled with an enzyme to produce a color change?

Accepted Answer

Indirect ELISA

Question 9

A laboratory uses PCR to detect the presence of a pathogen in a blood sample. What is a key advantage of this technique?

Accepted Answer

It can amplify minute quantities of nucleic acids, allowing detection even when the pathogen is present in low numbers.

Question 10

Which of the following best describes the principle behind the Western blot technique?

Accepted Answer

It separates proteins by electrical charge, then uses labeled antibodies to detect specific proteins.

Question 11

Which of the following technologies identifies microbes based on their protein fingerprints?

Accepted Answer

Mass spectrometry

Question 12

A patient’s serum is serially diluted and tested for agglutination with a specific antigen. The highest dilution that still shows agglutination is 1/320. What is the antibody titer?

Accepted Answer

$$320$$

Question 13

Which of the following statements about the use of microarrays in microbial diagnostics is correct?

Accepted Answer

Microarrays can simultaneously detect thousands of different microbial genes in a single test.

Question 14

Which of the following is a drawback of phenotypic methods that require culturing the pathogen?

Accepted Answer

They can take at least 18 to 24 hours, delaying diagnosis and treatment.

Question 15

Which of the following statements about fluorescent in situ hybridization (FISH) is correct?

Accepted Answer

FISH uses fluorescently labeled probes to detect specific nucleic acid sequences in intact cells.

Question 16

A patient is suspected of having tuberculosis. Which in vivo test would be used to determine prior exposure to Mycobacterium tuberculosis?

Accepted Answer

Tuberculin skin test (PPD injection)

Question 17

Which of the following best explains why proper labeling and patient history are crucial in specimen collection for microbial identification?

Accepted Answer

They ensure that the correct test is performed and results are interpreted in the right clinical context.

Question 18

Which of the following is a major benefit of 'lab on a chip' technologies for global public health?

Accepted Answer

They allow rapid, easy-to-use genetic testing in resource-limited settings.

Question 19

Which of the following best describes the principle of the complement fixation test?

Accepted Answer

It detects the presence of antibodies by their ability to fix complement and prevent lysis of red blood cells.

Question 20

Which of the following is a correct pairing of ELISA type and what it detects?

Accepted Answer

Direct ELISA detects antigens; indirect ELISA detects antibodies.

Chapter 15: Diagnosing Infections – Microbial Identification and Laboratory Techniques

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