Deck 13: Acid-Fast Bacilli Cultures

Question 1

1A microbiology laboratory wants to be able to stain, read, and report acid-fast smears for their patient population as well as process, culture, and read mycobacterial cultures. It also needs to be able to identify Mycobacterium tuberculosis as well as other species. This laboratory wants to provide Level ____ services.

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

Answer 1

3

Question 2

Tuberculin skin testing is an element of safety in any laboratory regardless of the level of service provided. This test is performed every __________________ on microbiology personnel.

A) 2 years
B) 1.5 years
C) year
D) 6 months

Answer 2

year

Question 3

The use of open flames is no longer an option in most clinical laboratories due to the potential for

A) aerosolization of organisms.
B) poisoning due to gas fumes.
C) fire due to gas fumes.
D) melting the loops and needles during sterilization.

Answer 3

aerosolization of organisms.

Question 4

An individual is having trouble bringing up a good sputum specimen for mycobacterial culture. Another specimen option for this individual includes

A) gastric lavage.
B) bronchial washing.
C) induced sputum.
D) all of the above.
E) b and c.

Question 5

What constitutes an appropriate urine specimen for acid-fast bacilli culture?

A) 5 to 10 mL of urine
B) Urine collected 30 minutes, 1 hour, and 2 hours after ingestion of 20 to 30 mL of sterile distilled water
C) A minimum of 40 mL of a first morning specimen
D) A minimum of 40 mL of urine prior to eating the morning meal

Question 6

Given the following specimens, which one is considered unacceptable for acid-fast culture?

A) Bone marrow collected in a SPS tube
B) 24-hour pooled urine
C) Gastric lavage prior to eating
D) Blood collected in a heparin tube

Question 7

The difference between the Ziehl-Neelsen (ZN) stain and the Kinyoun (K) stain is the

A) final stain reactions.
B) initial stain used.
C) use of heat in the ZN procedure.
D) secondary stain used.

Question 8

One disadvantage of the fluorochrome stain for acid-fast bacilli is

A) it takes longer to scan the slide.
B) the lower contrast between the organism and background.
C) the rapid-growing species may not fluoresce.
D) training to read the slides takes longer.

Question 9

Using the image provided and knowing the primary stain used was not heated after application, one can determine this slide depicts a
Source: CDC and Ronald W. Smithwick

A) positive Kinyoun reaction.
B) positive Ziehl-Neelsen reaction.
C) negative Kinyoun reaction.
D) negative Ziehl-Neelsen reaction.

Question 10

A microbiologist is reading the stained fluorochrome patient slides processed that day. Review the image provided for a review of the first slide he reads.
Source: CDC and Ronald W. Smithwick
Each subsequent patient slide demonstrates similar organisms observed in the first slide. Upon completing the set of slides, he should

A) report all slides as positive for acid-fast bacilli.
B) report all slides as negative for acid-fast bacilli.
C) consider the possibility of cross-contamination from the immersion lens.
D) consider the possibility of contamination during specimen plating.

Question 11

Which of the following specimens does not require digestion and decontamination prior to media inoculation?

A) Pleural fluid
B) Catheterized urine
C) Wound aspirate
D) Gastric lavage

Question 12

When processing a sputum specimen for acid-fast bacilli using the NALC-NaOH procedure, which reagent is mucolytic?

A) NaOH
B) NALC
C) Oxalic acid
D) Bleach

Question 13

Malachite green is added to egg-based medium to

A) enhance the growth of Mycobacterium spp.
B) coagulate the egg protein present.
C) inhibit growth of contaminating bacteria.
D) provide nutrition.

Question 14

Most commercial systems, for the detection of mycobacteria, use __________
Medium.

A) liquid
B) agar-based
C) egg-based
D) a combination of b and c

Question 15

Mycobacterial medium with a X factor strip and incubated at 30°C in CO₂ is

A) Mycobacterium marinum.
B) M. tuberculosis.
C) M. ulcerans.
D) M. haemophilum.

Question 16

Serpentine cording is observed on an acid-fast stain from liquid medium. This organism is most likely

A) Mycobacterium tuberculosis.
B) M. avium.
C) M. intracellulare.
D) M. gordonae.

Question 17

Which of the following physiological groups are slow growers and produce an

A) Scotochromogen
B) Nonphotochromogen
C) Photochromogen
D) Mycobacterium tuberculosis complex

Question 18

Molecular methods, for detection of mycobacteria, are available for testing

A) direct specimens.
B) growth on solid medium.
C) growth in liquid medium.
D) all of the above. e. b and c.

Question 19

Which of the following reactions is incorrect for Mycobacterium tuberculosis?

A) Niacin positive
B) Nitrate positive
C) 68°C catalase positive
D) Serpentine cording

Question 20

Which test should be used to determine if Mycobacterium tuberculosis colonies isolated from the sputum of two patients housed in the same room are the same organisms?

A) DNA amplification
B) Restriction fragment length polymorphism
C) Nucleic acid probe
D) Phenotypic, biochemical, and susceptibility results