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BACTERIOLOGY > HARR EE2 7.8 > Flashcards

HARR EE2 7.8 Flashcards

1
Q 
The best specimen for recovery of the mycobacteria
from a sputum sample is:
A. First morning specimen
B. 10-hour evening specimen
C. 12-hour pooled specimen
D. 24-hour pooled specimen
A

A. First morning specimen

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2
Q

What concentration of sodium hydroxide (NaOH)
is used to prepare a working decontamination
solution for the processing of not normally sterile
specimens for mycobacteria?
A. 1% NaOH
B. 4% NaOH
C. 8% NaOH
D. 12% NaOH

A

B. 4% NaOH

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3
Q

Which is the most appropriate nonselective
medium for recovery of mycobacteria from a
heavily contaminated specimen?
A. Löwenstein–Jensen agar
B. Middlebrook 7H10 agar
C. Petragnani’s agar
D. American Thoracic Society medium

A

C. Petragnani’s agar

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4
Q

Mycobacteria stained by the Ziehl–Neelsen or
Kinyoun methods with methylene blue
counterstain are seen microscopically as:
A. Bright red rods against a blue background
B. Bright yellow rods against a yellow background
C. Orange-red rods against a black background
D. Bright blue rods against a pink background

A

A. Bright red rods against a blue background

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5
Q

Acid-fast staining of a smear prepared from
digested sputum showed slender, slightly curved,
beaded, red mycobacterial rods. Growth on
Middlebrook 7H10 slants produced buff-colored
microcolonies with a serpentine pattern after
14 days at 37°C. Niacin and nitrate reduction
tests were positive. What is the most probable
presumptive identification?
A. Mycobacterium tuberculosis
B. Mycobacterium ulcerans
C. Mycobacterium kansasii
D. Mycobacterium avium–intracellulare complex

A

A. Mycobacterium tuberculosis

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6
Q

Which organism, associated with tuberculosis in
cattle, causes tuberculosis in humans, especially in
regions where dairy farming is prevalent?
A. Mycobacterium avium–intracellulare complex
B. Mycobacterium kansasii
C. Mycobacterium marinum
D. Mycobacterium bovis

A

D. Mycobacterium bovis

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7
Q

Which of the following organisms are used as
controls for rapid growers and slow growers?
A. Mycobacterium fortuitum and Mycobacterium
tuberculosis
B. Mycobacterium avium-intracellulare complex
and Mycobacterium tuberculosis
C. Mycobacterium chelonei and Mycobacterium
fortuitum
D. Mycobacterium kansasii and Mycobacterium
tuberculosis

A

A. Mycobacterium fortuitum and Mycobacterium

tuberculosis

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8
Q

Which of the following Mycobacterium spp.
produce(s) pigmented colonies in the dark (is a
scotochromogen)?
A. M. szulgai
B. M. kansasii
C. M. tuberculosis
D. All of these options

A

A. M. szulgai

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9
Q 
All of the following mycobacteria are associated
with skin infections except:
A. Mycobacterium marinum
B. Mycobacterium haemophilum
C. Mycobacterium ulcerans
D. Mycobacterium kansasii
A

D. Mycobacterium kansasii

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10
Q

All of the following Mycobacterium spp. produce
the enzyme required to convert niacin to niacin
ribonucleotide except:
A. M. kansasii
B. M. tuberculosis
C. M. avium–intracellulare complex
D. M. szulgai

A

B. M. tuberculosis

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11
Q

The catalase test for mycobacteria differs from that
used for other types of bacteria by using:
A. 1% H2O2 and 10% Tween 80
B. 3% H2O2 and phosphate buffer, pH 6.8
C. 10% H2O2 and 0.85% saline
D. 30% H2O2 and 10% Tween 80

A

D. 30% H2O2 and 10% Tween 80

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12
Q

Growth inhibition by thiophene-2-carboxylic
hydrazide (T2H) is used to differentiate
M. tuberculosis from which other Mycobacterium
specie?
A. M. bovis
B. M. avium–intracellulare complex
C. M. kansasii
D. M. marinum

A

A. M. bovis

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13
Q

Which of the following Mycobacterium spp. is best
differentiated by the rapid hydrolysis of Tween 80?
A. M. fortuitum
B. M. chelonae
C. M. kansasii
D. M. gordonae

A

C. M. kansasii

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14
Q

Mycobacteria isolated from the hot water
system of a hospital grew at 42°C. Colonies on
Löwenstein–Jensen medium were not pigmented
after exposure to light and were negative for niacin
accumulation and nitrate reduction. The most
likely identification is:
A. Mycobacterium xenopi
B. Mycobacterium marinum
C. Mycobacterium ulcerans
D. Mycobacterium haemophilum

A

A. Mycobacterium xenopi

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15
Q 
A Mycobacterium species recovered from a patient with AIDS gave the following results:
- Niacin = Neg 
- T2H = +
- Tween 80 hydrolysis = Neg 
- Nitrate reduction = Neg
- Heat-stable catalase (68°C) = ±
- Nonphotochromogen
What is the most likely identification?
A. M. gordonae
B. M. bovis
C. M. avium–intracellulare complex
D. M. kansasii
A

C. M. avium–intracellulare complex

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16
Q 
The urease test is needed to differentiate
Mycobacterium scrofulaceum from which 
of the following mycobacteria?
A. M. gordonae
B. M. kansasii
C. M. avium–intracellulare complex
D. M. bovis
A

A. M. gordonae

17
Q

A laboratory provides the following services for
identification of mycobacteria:
Acid-fast staining of clinical specimens
Inoculation of cultures
Shipment of positive cultures to a reference
laboratory for identification
According to the American Thoracic Society’s
definition for levels of service this laboratory is:
A. Level I
B. Level II
C. Level III
D. Level IV

A

A. Level I

18
Q

According to the College of American Pathologists
(CAP) guidelines, which services for mycobacteria
would be performed by a Level II laboratory?
A. No procedures performed
B. Acid-fast staining, inoculation, and referral to a
reference laboratory
C. Isolation and identification of Mycobacterium
tuberculosis; preliminary identification of other
species
D. Definitive identification of all mycobacteria

A

B. Acid-fast staining, inoculation, and referral to a

reference laboratory

19
Q

Culture of a skin (hand) wound from a manager of a tropical fish store grew on Löwenstein–Jensen agar slants at 30°C in 10 days but did not grow on the same media at 37°C in 20 days. Given the following results, what is the most likely identification?

  • Photochromogen = +
  • Niacin = Neg
  • Urease = +
  • Heat-stable catalase (68°C) = Neg
  • Nitrate reduction = Neg
  • Tween 80 hydrolysis = +

A. Mycobacterium marinum
B. Mycobacterium kansasii
C. Mycobacterium avium-intracellulare complex
D. Mycobacterium tuberculosis

A

A. Mycobacterium marinum

20
Q

Which nonpathogenic Mycobacterium specie is
isolated most often from clinical specimens and is
called the “tapwater bacillus”?
A. M. kansasii
B. M. avium–intracellulare complex
C. M. leprae
D. M. gordonae

A

D. M. gordonae

21
Q

Which of the following drugs are first-line
antibiotics used to treat classic tuberculosis for
which susceptibility testing is performed by the
disk diffusion method on Middlebrook 7H10 or
7H11 agar plates?
A. Ampicillin, penicillin, streptomycin, and
carbenicillin
B. Ampicillin, penicillin, and methicillin
C. Vancomycin, methicillin, and carbenicillin
D. Isonicotinic acid hydrazide (INH), rifampin,
ethambutol, and pyrazinamide

A

D. Isonicotinic acid hydrazide (INH), rifampin,

ethambutol, and pyrazinamide

22
Q

How long should Mycobacterium tuberculosis–positive cultures be kept by the
laboratory after identification and antibiotic susceptibility testing have been performed?
A. 1–2 months
B. 2–4 months
C. 5–6 months
D. 6–12 months

A

D. 6–12 months

23
Q

According to the reporting standards of the
American Thoracic Society, one or more acid-fast
bacilli (AFB) per oil immersion field (1,000×) are
reported as:
A. Numerous or 3+
B. Few or 2+
C. Rare or 1+
D. Indeterminate; a new specimen should be
requested

A

A. Numerous or 3+

24
Q

Which of the following Mycobacterium spp. would
be most likely to grow on a MacConkey agar plate?
A. M. chelonae–fortuitum complex
B. M. ulcerans
C. M. marinum
D. M. avium–intracellulare complex

A

A. M. chelonae–fortuitum complex

25
Q 
Rapid methods for identifying classic infection
with M. tuberculosis include:
A. Gas–liquid chromatography
B. Nucleic acid probes
C. Acid-fast smears
D. All of these options
A

D. All of these options

26
Q

Individuals showing a positive purified protein
derivative (PPD) skin test for M. tuberculosis are
usually:
A. Infective
B. Symptomatic of pulmonary disease
C. Latently infected
D. Falsely positive

A

C. Latently infected

27
Q 
Which of the following Mycobacterium species is
diagnosed by means other than culture?
A. M. leprae
B. M. bovis
C. M. canetti
D. M. avium
A

A. M. leprae

28
Q

Which M. avium complex (MAC) organism is the
most frequently isolated mycobacterium from
AIDS patients?
A. M. avium
B. M. intracellulare
C. M. scrofulaceum
D. M. bovis

A

A. M. avium

29
Q

Which mycobacterium of the M. tuberculosis
complex fails to grow in culture and has a
characteristic “croissant-like” morphology in
stained smears?
A. M. africanum
B. M. microti
C. M. bovis
D. M. leprae

A

B. M. microti

30
Q 
Which two mycobacteria commonly isolated from
subcutaneous skin have an optimal growth
temperature of 30°C?
A. M. haemophilum and M. ulcerans
B. M. kansasii and M. xenopi
C. M. gordonae and M. avium
D. M. simiae and M. avium
A

A. M. haemophilum and M. ulcerans

31
Q 
Which mycobacterium is associated with Crohn’s
disease?
A. M. marinum
B. M. paratuberculosis
C. M. avium
D. M. gordonae
A

B. M. paratuberculosis

32
Q 
Which temperature range is ideal for the recovery
of M. marinum?
A. 24°C–26°C
B. 30°C–32°C
C. 42°C–44°C
D. 44°C–48°C
A

B. 30°C–32°C

BACTERIOLOGY (3 decks)

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