Deck 26: Mycobacterium Species

Question 1

Which of the following Mycobacterium spp. is considered fastidious?

A) M. haemophilum
B) M. avium-intracellulare complex
C) M. tuberculosis
D) M. fortuitum complex

Answer 1

M. haemophilum

Question 2

The source for many Mycobacterium spp. is

A) soil.
B) water.
C) animals.
D) all of the above.
E) a and b.

Answer 2

all of the above.

Question 3

All of the following statements are true concerning atypical Mycobacterium spp. except

A) Immunocompromised individuals are at highest risk for infection.
B) They are spread via person-to-person contact.
C) They present with respiratory illness.
D) Transmission is via environmental sources.

Answer 3

They are spread via person-to-person contact.

Question 4

Infections due to tubercle bacilli are

A) typically due to exposure to the organisms in soil and water.
B) not seen in industrialized countries.
C) characterized by the formation of cheese-like necrosis and lesions.
D) only found in immunocompromised individuals.

Question 5

If a slow-growing, acid-fast bacillus is able to produce an orange pigment when grown in dark or light, it is classified as Runyoun group

A) I - photochromogen
B) II - Scotochromogen
C) III - Nonphotochromogen
D) IV - Rapid grower

Question 6

Mycobacterium fortuitum is classified as a

A) photochromogen.
B) scotochromogen.
C) nonphotochromogen.
D) rapid grower.

Question 7

Mycobacterium tuberculosis is classified as a

A) photochromogen.
B) scotochromogen.
C) nonphotochromogen.
D) none of the above.

Question 8

An acid-fast bacillus is recovered from a bronchial washing on Lowenstein-Jensen medium after 18 days at 35°C with CO₂. Initially the colonies are buff, raised, and rough when grown in the dark. After exposure to light, no change in pigmentation is noted. On examination at 10X magnification, the colonies reveal serpentine cording. Which of the following biochemical test reactions will confirm the identity of the most likely etiologic agent?

A) Niacin and nitrate negative
B) Niacin and nitrate positive
C) Niacin positive and nitrate negative
D) Niacin negative and nitrate positive

Question 9

A slow-growing, acid-fast bacillus provides the following reactions:
Which of the following patient history/specimen types was the original source for this organism?

A) Stool from a 44-year-old male with HIV
B) Sputum from an 18-year-old female illegal alien from Mexico
C) Skin lesion from a 39-year-old female who owns a tropical fish store
D) Lymph node from a 4-month-old male after receiving the BCG vaccine

Question 10

The acid-fast colonies in the image provided demonstrated no color change with exposure to light.
Source: CDC and Dr. George Kubica
Given that the organism produces a yellow color on the niacin accumulation test and pink color on the nitrate reduction test, what additional characteristic is considered presumptive for this organism?

A) Serpentine cording
B) Rapid growth
C) Requirement for hemin
D) Growth at 30°C

Question 11

The presence of acid-fast bacilli in a skin lesion but the inability to grow the organism on Lowenstein-Jensen medium is characteristic for

A) Mycobacterium fortiutum.
B) M. haemophilum.
C) M. leprae.
D) b and c.

Question 12

A skin lesion grows an acid-fast bacilli on Lowenstein-Jensen agar at 30°C but not 35°C. This organism will be a

A) scotochromogen.
B) photochromogen.
C) nonphotochromogen.
D) rapid grower.

Question 13

A sputum, submitted for AFB culture and smear, demonstrates the Kinyoun stain provided.
Source: CDC and Dr. George P. Kubica
The organism isolated on Lowenstein-Jensen agar provided the following reactions:
Pigment: buff-colored colonies in the dark and yellow when exposed to light
This organism is

A) Mycobacterium gordonae.
B) M. marium.
C) M. kansasii.
D) M. bovis.

Question 14

Select the correct organism/unique characteristic.

A) Mycobacterium gordonae/cording
B) M. marinum/rate of growth
C) M. leprae/nonculturable
D) M. haemophilum/growth at 42°C

Question 15

The diagnosis of Hansen's disease is made by

A) demonstration of acid-fast bacilli in tissue.
B) presumptive identification based on colony morphology.
C) biochemical testing.
D) all of the above.
E) b and c.

Question 16

To differentiate the species within the Mycobacterium avium complex, one would use

A) tellurite reduction.
B) pyrazinamidase.
C) 16sRNA genotyping.
D) a and c.
E) b and c.

Question 17

Which of the following organisms morphologically resembles Mycobacterium tuberculosis but is nitrate and niacin negative?

A) Mycobacterium fortuitum
B) M. bovis
C) M. scrofulaceum
D) M. kansasii

Question 18

Which of the following organisms is used to create the BCG vaccine?

A) Buff colored colony that is niacin and nitrate negative
B) Buff colored colony that is niacin negative and nitrate positive
C) Buff colored colony hat is niacin and nitrate positive
D) Orange-pigmented colony that is nitrate negative

Question 19

Molecular testing is a valuable tool useful in the detection of

A) M. tuberculosis.
B) M. haemophilum.
C) M. leprae.
D) all of the above.

Question 20

The use of multiple drugs to treat tuberculosis is necessary to ensure

A) the patient will be compliant and take at least one of the drugs.
B) synergy of the drugs' modes of action.
C) resistance does not develop.
D) adequate treatment.