Deck 26: Mycobacterium Tuberculosis and Nontuberculous Mycobacteria

Question 1

What is the single most important piece of equipment in a mycobacterial laboratory?

A) Ultraviolet lights
B) Covered centrifuge
C) Biological safety cabinet
D) CO₂ incubator

Answer 1

C

Question 2

What constituent of LJ medium is added to suppress the growth of gram-positive bacteria?

A) Carbolfuchsin
B) Malachite green
C) Gentian purple
D) Mercurochrome

Answer 2

B

Question 3

What are scotochromogens?

A) Species that produce carotene pigment upon exposure to light
B) Species that produce pigment in the light or the dark
C) Species whose colonies remain buff colored after exposure to light
D) Species whose colonies fluoresce under ultraviolet light

Answer 3

B

Question 4

What is the recommended contact time for most disinfectants in a mycobacteriology laboratory?

A) 5 minutes
B) 10 to 30 minutes
C) 10 minutes
D) 60 minutes

Question 5

What are photochromogens?

A) Species that produce carotene pigment upon exposure to light
B) Species that produce pigment in the light or the dark
C) Species whose colonies remain buff colored after exposure to light
D) Species whose colonies fluoresce under ultraviolet light

Question 6

All of these stains are commonly used to visualize mycobacteria on a smear, except

A) Ziehl-Neelsen.
B) Kinyoun.
C) auramine.
D) acridine orange.

Question 7

A microbiologist notices growth on a LJ slant that is a buff color, rough, and seems arranged in a cord. It has taken these organisms 4 weeks to grow. What is the most probable organism?

A) Mycobacterium leprae
B) M. avium
C) M. tuberculosis
D) M. marinum

Question 8

Middlebrook 7H10 and 7H11 media are enriched with all of the following, except

A) oleic acid.
B) bovine albumin.
C) heme.
D) beef catalase.

Question 9

What Mycobacterium spp. fails to grow in vitro?

A) Mycobacterium tuberculosis
B) M. leprae
C) M. avium
D) M. marinum

Question 10

What medium is recommended for the recovery of Mycobacterium haemophilum?

A) Sheep blood agar (SBA)
B) Chocolate
C) Polysaccharide egg antigen (PEA)
D) LJ

Question 11

How long does it take to detect most Mycobacterium spp. with the BACTEC method?

A) Less than 2 weeks
B) 3 weeks
C) 4 weeks
D) 6 weeks

Question 12

What are nonchromogens?

A) Species that produce carotene pigment upon exposure to light
B) Species that produce pigment in the light or the dark
C) Species whose colonies remain buff colored after exposure to light
D) Species whose colonies fluoresce under ultraviolet light

Question 13

What is the purpose of the digestion-decontamination processing of specimens submitted for mycobacterial culture?

A) To release all bacteria in the sample
B) To make the specimen easier to plate
C) To allow chemical decontaminants to kill nonmycobacterial organisms
D) To liquefy the outer cell wall of the mycobacteria so that they will grow faster

Question 14

How are mycobacterial infections typically transmitted?

A) By blood
B) By fomites
C) By sexual contact
D) By air

Question 15

What is the most sensitive and rapid primary isolation liquid media for Mycobacterium spp.?

A) Thioglycollate
B) Cooked meat
C) 5% NaCl broth
D) Middlebrook 7H12

Question 16

Decontaminating agents used in the decontamination-digestion process include all of the following, except

A) sodium hydroxide.
B) N-acetyl-1-cysteine.
C) benzalkonium chloride.
D) hydrochloric acid.

Question 17

What media are recommended for routine culturing of specimens for the recovery of acid-fast bacilli?

A) Löwenstein-Jensen (LJ) and liquid-based media
B) Middlebrook 7H10 and cooked meat broth
C) Sabouraud dextrose and LIM broth
D) Thiosulfate-citrate-bile salts-sucrose (TCBS) and thioglycollate broth

Question 18

What is the optimum culture incubation time for most mycobacteria associated with human disease?

A) 2 to 6 weeks
B) 1 to 2 weeks
C) 5 to 7 days
D) 3 to 5 days

Question 19

When designing a mycobacterial laboratory, the designers should include all the following engineering controls to keep the workers safe, except

A) inside air vents to outside.
B) non-recirculating ventilation system.
C) positive air pressure.
D) separate room from main laboratory.

Question 20

All of the following are traditional characteristics used to identify mycobacteria, except

A) rate of growth.
B) colony morphology.
C) Gram stain results.
D) pigmentation.

Question 21

If a person has had TB during his or her lifetime, how likely is it that the person will get the disease again?

A) 5% to 15%
B) 20% to 25%
C) 1%
D) 50%

Question 22

A patient with Hodgkin disease is feeling bad, so he visits his physician. The physician's clinical examination reveals submandibular lymphadenitis, subcutaneous nodules, painful swellings, ulcers progressing to abscesses, and draining fistulas. What organism is probably producing these symptoms?

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

Question 23

This disease is slowly progressive, malignant, and, if untreated, life threatening. It is characterized by skin lesions and progressive, symmetric nerve damage. Lesions of the mucous membranes of the nose may lead to destruction of the cartilaginous septum, resulting in nasal and facial deformities. What disease is this?

A) Hansen disease
B) Extrapulmonary TB
C) Non-Mycobacterium tuberculosis pulmonary disease
D) M. xenopi

Question 24

What classifies an organism as a multidrug-resistant Mycobacterium tuberculosis?

A) Resistance to at least isoniazid and rifampin
B) Resistance to isoniazid, rifampin, ethambutol, and streptomycin
C) Resistance to streptomycin and rifampin
D) Resistance to ciprofloxacin and imipenem

Question 25

What component of mycobacteria is used for identification in nucleic acid hybridization assays?

A) DNA
B) Ribosomal RNA
C) Transfer RNA
D) Messenger RNA

Question 26

How has the treatment of mycobacterial disease changed in light of the multidrug-resistant strains of mycobacteria that are being isolated?

A) Antimicrobial therapy is started sooner in the course of the disease.
B) More powerful antimicrobial agents are used to treat mycobacterial disease.
C) Combinations of three or four drugs are used instead of a single drug.
D) Patients are hospitalized for the duration of their disease.

Question 27

A 35-year-old man travels on a multidestination vacation over a 2 month period, including lengthy stops in tropical Africa and Southeast Asia. Six weeks after returning come home to the United States, he develops a productive cough, fatigue, weight loss, low-grade fever, and night sweats. What disease should the physician consider as a result of his travel history?

A) Streptococcal pneumonia
B) Primary atypical pneumonia
C) TB
D) Pneumonia caused by gram-negative rods

Question 28

What is the antigen used in the purified protein derivative (PPD) skin test?

A) A purified protein from the nucleus of Mycobacterium tuberculosis
B) A purified piece of DNA from M. tuberculosis
C) A purified protein from the cell wall of M. tuberculosis
D) A piece of ribosomal RNA from M. tuberculosis

Question 29

A sputum culture from a patient in Texas has buff colored colonies growing in approximately 4 weeks. After exposure to light, the colonies turn intense yellow. This isolate is most likely

A) M. scrofulaceum.
B) M. kansasii.
C) M. fortuitum.
D) M. xenopi.

Question 30

The Centers for Disease Control and Prevention (CDC) recommends all the following drugs for the treatment of Mycobacterium tuberculosis, except

A) ethambutol.
B) isoniazid.
C) rifampin.
D) ciprofloxacin.

Question 31

All of the following are biochemical tests for the identification of Mycobacterium spp., except

A) niacin.
B) nitrate.
C) catalase.
D) PYR.

Question 32

A child presents to his physician with fever, a nonproductive cough, and shortness of breath. The physician orders a routine sputum culture and an acid-fast bacillus culture and smear. The smear shows red organisms arranged in ropes. What is the most probable cause of this child's fever and cough?

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

Question 33

The most common nontuberculosis mycobacterium (NTM) infecting humans

A) M. marinum.
B) M. ulcerans.
C) M. haemophilium.
D) M. avium-intracellulare complex.

Question 34

All of the following are biochemical tests for the identification of Mycobacterium spp., except

A) gelatin liquefaction.
B) hydrolysis of Tween 80.
C) iron uptake.
D) arylsulfatase.