Deck 26: Mycobacterium Tuberculosis and Nontuberculous Mycobacteria

Question 1

What type of media is recommended for the recovery of Mycobacterium haemophilum?

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

Answer 1

B
A chocolate agar plate should be included in the primary isolation media for skin and other body surface specimens for the recovery of M.haemophilum, which requires ferric ammonium citrate or hemin for growth.Alternatively, hemin (X) strips or disks used for the identification of Haemophilus spp.can be placed on Middlebrook agar plates.

Question 2

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

A)Löwenstein-Jensen 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

Answer 2

A
Because some isolates do not grow on a particular agar and each type of culture medium offers certain advantages, a combination of culture media is generally recommended for primary isolation.The use of a solid-based medium, such as Löwenstein-Jensen (LJ) medium, in combination with a liquid-based medium is recommended for routine culturing of specimens for the recovery of AFB.

Question 3

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

Answer 3

B
The following disinfectants are used in the mycobacterial laboratories to disinfect working surfaces: Phenol soap, 10 to 30 minutes; sodium hypochlorite, 10 to 30 minutes; formaldehyde, 30 minutes; and phenol, 10 to 30 minutes.

Question 4

What Mycobacterium spp.fails to grow in vitro?

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

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

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

A)inside air vents to outside.
B)nonrecirculating ventilation system.
C)negative air pressure.
D)separate room from main laboratory.

Question 7

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 8

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 9

What constituent of Löwenstein-Jensen (LJ) medium is added to suppress the growth of gram-positives?

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

Question 10

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 11

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 12

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 13

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 14

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

Question 15

How are mycobacterial infections transmitted?

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

Question 16

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 17

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 18

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

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

Question 19

A microbiologist is checking the mycobacteria cultures.She notices growth in one tube of Löwenstein-Jensen (LJ) 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 20

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

Question 21

All of the following are common extrapulmonary infection sites for tuberculosis except:

A)kidneys.
B)gastrointestinal.
C)liver.
D)spleen.

Question 22

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

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

Question 23

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

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

Question 24

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 25

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 26

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.

Question 27

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's disease
B)Extrapulmonary tuberculosis
C)Non-Mycobacterium tuberculosis pulmonary disease
D)M.xenopi

Question 28

A patient with Hodgkin's disease is feeling bad, so he pays a visit to 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 29

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 30

A sputum culture from a patient in Texas has colonies that grow buff colored colonies 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 31

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

A)Antibiotic therapy is started sooner in the course of the disease.
B)More powerful antibiotics 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 32

If a person has had tuberculosis 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 33

A child visits his doctor because he has had a fever and a nonproductive cough.The child is also short of breath.The doctor orders a routine sputum culture and an acid-fast bacillus (AFB) 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 34

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)Tuberculosis (TB)
D)Pneumonia caused by gram-negative rods