Deck 12: Detection and Identification of Microorganisms

Question 1

HIV genotyping is performed for which of the following reasons?

A) Monitor development of antiretroviral drug resistance
B) Confirm HIV infection
C) Quantify amount of HIV in the patient
D) Determine source of HIV

Answer 1

Monitor development of antiretroviral drug resistance

Question 2

The ability of a typing method to distinguish between unrelated strains is which of the following criteria?

A) Ease of use
B) Discriminatory power
C) Reproducibility
D) Ease of interpretation

Answer 2

Discriminatory power

Question 3

Which of the following genes is the target in molecular-based assays that are used to quantify the amount of HIV in a patient?

A) Protease
B) gag
C) Hemagglutinin
D) ctx-m

Answer 3

gag

Question 4

In a PCR assay of DNA isolated from a nasopharyngeal swab, amplification using primers to IS481 was positive and using primers to IS1001 was negative. All controls were acceptable. Which of the following organisms was present in this sample?

A) Bordetella pertussis
B) Bordetella parapertussis
C) Bordetella holmesii
D) Legionella pneumophila

Question 5

Which of the following genes is a target in molecular-based assays and confers resistance to vancomycin in the enterococci?

A) inhA
B) mecA
C) vanA
D) gyrA

Question 6

In the interpretation of pulsed field gel electrophoresis patterns, what is the minimum number of bands that can differ between two organisms before those organisms are determined to be unrelated?

A) 2
B) 3
C) 6
D) 7

Question 7

A PCR assay that uses short primers that amplify random sequences found throughout the genome of the test organism is what variation of PCR?

A) Arbitrarily primed
B) Amplified fragment length polymorphism
C) Repetitive extragenic palindromic
D) Enterobacterial repetitive intergenic consensus

Question 8

Which of the following is an important characteristic of a target sequence for molecular detection of a microorganism?

A) The sequence must be very long.
B) The sequence must be shared by many different organisms.
C) The sequence must be unique to the target organism.
D) The sequence must contain many restriction enzyme sites.

Question 9

Pulsed field gel electrophoresis has been performed on two isolates of Escherichia coli from the blood of newborns in the same neonatal unit. The banding pattern of one isolate had two differences from the banding pattern of the other isolate. Which of the following is the correct interpretation of these results?

A) The isolates are indistinguishable.
B) The isolates are closely related.
C) The isolates are not related.
D) The isolates are different species.

Question 10

DNA is isolated from a test organism and cut with restriction enzymes. The fragments are ligated to adapters that are complementary to primers that are added to perform two rounds of PCR. The PCR products are separated by gel electrophoresis and analyzed. Which of the following methods was described?

A) Restriction fragment length polymorphism
B) Amplified fragment length polymorphism
C) Pulsed field gel electrophoresis
D) Arbitrarily primed PCR

Question 11

When a typing method is repeated and the results are the same each time, the method has high:

A) Ease of test performance
B) Discriminatory power
C) Typing capacity
D) Reproducibility

Question 12

Which of the following is the molecular target for most epidemiological investigations of Mycobacterium tuberculosis?

A) katG
B) inhA
C) IS6110
D) IS481

Question 13

Which of the following typing methods is an RNA test?

A) Plasmid analysis
B) Ribotyping
C) PCR-RFLP
D) PFGE

Question 14

PCR with RFLP analysis and reverse hybridization is the principle of which of the following commercial assays?

A) TRUGENE
B) Cleavase fragment length polymorphism
C) Amplicor HCV
D) Inno-LiPA

Question 15

Which of the following is a genotypic method for typing organisms?

A) Antibiogram patterns
B) Pulsed field gel electrophoresis
C) Serotyping
D) Bacteriophage typing

Question 16

What will be observed in a PCR test of a true negative sample for the sample, positive control, negative control, and amplification control, respectively?

A) Negative, positive, negative, positive
B) Negative, positive, negative, negative
C) Negative, negative, negative, negative
D) Negative, negative, negative, positive

Question 17

What is a convenient way to concentrate organisms present in cerebrospinal fluid or urine samples before testing?

A) Heat the specimen to evaporate fluid.
B) Centrifuge the specimen.
C) Freeze and thaw the specimen.
D) Use as large volume as possible in the assay.

Question 18

Which of the following molecular-based assays targets rRNA?

A) NASBA for hepatitis C virus
B) TMA for Mycobacterium tuberculosis
C) Accuprobe for M. tuberculosis
D) Linear Array Genotyping for HPV

Question 19

A positive control is added (spiked) into a test specimen. The test results of the specimen alone and the spiked mixture are negative. What does this most likely indicate?

A) The specimen is negative.
B) The specimen is positive.
C) The specimen contains an inhibitor.
D) The positive control contains an inhibitor.

Question 20

A PCR assay using primers specific for the autolysin gene (lytA) was performed on a sputum specimen from a 10-year-old girl. The specimen was positive, and all controls were acceptable. Which of the following is the best interpretation of these results?

A) Definitive diagnosis of clinically significant Streptococcus pneumoniae pneumonia is made.
B) Streptococcus pneumoniae is present, but clinical significance is questionable.
C) Mycobacterium tuberculosis is detected, and the girl should be isolated.
D) The patient has Chlamydophila pneumoniae pneumonia.

Question 21

Which of the following targets are used to type molds?

A) ITS
B) 16s RNA
C) ERIC
D) REP

Question 22

Which is a flow cytometry test?

A) Hybrid capture
B) NASBA
C) TMA
D) HPV OncoTect

Question 23

Which virus does not share sequence homology with the others?

A) JC
B) BK
C) HCV
D) SV40

Question 24

The following methods that are used to determine the HIV viral load in a newly diagnosed patient. Which uses signal amplification?

A) NASBA
B) bDNA
C) RT-PCR
D) Sequencing

Question 25

What characteristic of parasites complicates molecular testing?

A) Unusual sequence content
B) Resistance to disruption and lysis
C) Wide prevalence in developed countries
D) Similar microscopic morphology