Test Questions & Answers Ch11 Detection And Identification

Chapter 11: Detection and Identification of Microorganisms

Multiple Choice

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

A. Antibiogram patterns

B. Pulsed-field gel electrophoresis

C. Serotyping

D. Bacteriophage typing

OBJ: 11.5

2. 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.

OBJ: 11.6

3. 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 of a volume as possible in the assay.

OBJ: 11.5

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

A. negative; positive; negative; positive

B. negative; positive; negative; negative

C. negative; negative; negative; negative

D. negative; negative; negative; positive

OBJ: 11.6

5. Which of the following is an important characteristic of a target sequence for the 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.

OBJ: 11.5

6. Pulsed-field gel electrophoresis has been performed on two isolates of Escherichia coli that have been isolated from the blood of newborns in the same neonatal unit. The banding pattern of the two isolates differed by two bands. 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 possibly related.

D. The isolates are different.

Obj: 11.7

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

A. katG

B. inhA

C. IS6110

D. IS481

OBJ: 11.1

8. Which of the following typing methods is an RNA test?

A. Plasmid analysis

B. Ribotyping

C. PCR-RFLP

D. PFGE

OBJ: 11.5

9. 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 is described?

A. Restriction fragment length polymorphism

B. Amplified fragment length polymorphism

C. Pulsed-field gel electrophoresis

D. Arbitrarily primed PCR

OBJ: 11.5

10. In the interpretation of pulsed-field gel electrophoresis patterns, one genetic difference can result in how many fragment differences?

A. None

B. One

C. Two-three

D. Four-Six

OBJ: 11.7

11. 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

OBJ: 11.7

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

A. Typing capacity

B. Discriminatory power

C. Reproducibility

D. Ease of interpretation

OBJ: 11.5

13. 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.

OBJ: 11.5

14. 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

OBJ: 11.4

15. A PCR assay on DNA isolated from a nasopharyngeal swab was performed, with the following results: 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

OBJ: 11.5

16. A PCR assay using primers specific for the autolysin (lytA) gene 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 Streptococcus pneumoniae pneumonia.

B. S. pneumoniae is present, but the clinical significance is questionable.

C. Mycobacterium tuberculosis is detected, and the girl should be isolated.

D. The patient has Chlamydophila pneumoniae pneumonia.

OBJ: 11.5

17. Which of the following combinations of molecular-based assays and detected organisms has been approved by the Food and Drug Administration?

A. NASBA for hepatitis C virus

B. TMA for Mycobacterium tuberculosis

C. Hybridization protection assay for group A streptococci

D. Sequencing for Neisseria gonorrhoeae

OBJ: 11.5

18. qPCR with multiple primer pairs and probes describes which of the following assays?

A. TRUGENE

B. Cleavase fragment length polymorphism

C. Amplicor HCV

D. BioFire

OBJ: 11.3

19. HIV genotyping is performed for which of the following reasons?

A. Monitor development of antiretroviral drug resistance

B. Confirmation of HIV infection

C. Quantify amount of HIV in the patient

D. Determine source of HIV

OBJ: 11.4

20. 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

OBJ: 11.5

21. Which is a flow cytometry test?

A. Hybrid capture

B. NASBA

C. TMA

D. HPV Oncotect

OBJ: 11.3

22. Which virus shares sequence homology with the JC/BK virus?

A. HPV

B. HTLV

C. HCV

D. SV40

OBJ: 11.5

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

A. NASBA

B. bDNA

C. RT-PCR

D. Sequencing

OBJ: 11.5

24. Which of the following targets is used to type molds?

A. ITS

B. 16s RNA

C. ERIC

D. REP

OBJ: 11.5

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. Microscopic morphology

OBJ: 11.5

26. According to Tenover rules, what is the relationship between two organisms with three PFGE band differences?

A. Distantly related

B. Closely related

C. Unrelated

D. Identical

OBJ: 11.7

27. MRSA derives resistance to beta-lactam antibiotics through which mechanism?

A. Chemical cleavage

B. Altered cell wall

C. Altered cell membrane

D. Protein binding

OBJ: 11.4

28. Which assay has the highest ease of interpretation?

A. PFGE

B. REP

C. ERIC

D. RAPD

OBJ: 11.4

29. Which can cause a false-positive result for a target organism?

A. Sequence polymorphisms in the organism

B. Lack of amplification control

C. Amplification of nonviable organisms

D. Loss of plasmid

OBJ: 11.6

30. Which method is based on naturally repeated sequences in bacterial DNA?

A. qPCR

B. bDNA

C. ERIC

D. TMA

OBJ: 11.7