Deck 26: Mycobacterium Tuberculosis and Other Nontuberculosis Mycobacteria

Question 1

How are mycobacterial infections transmitted?

A) By blood
B) By respiratory droplet
C) By sexual contact
D) By air

Answer 1

D
The serious nature of tuberculosis disease and the usual airborne route of infection require that special safety precautions be used by anyone handling mycobacterial specimens.

Question 2

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

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

Answer 2

C
Because the route of infection by mycobacteria is primarily through inhalation,it is essential that the dispersal of organisms into the air be minimized and that inhalation of airborne bacilli be avoided.The biologic safety cabinet is the single most important piece of equipment in a mycobacteriology laboratory.

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 labs 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

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 5

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

A) Lowenstein-Jensen and mycobacterial growth indicator tube
B) Middlebrook 7H10 and cooked meat broth
C) Sabouraud dextrose and LIM broth
D) Thiosulfate-citrate-bile salts-sucrose (TCBS) and thioglycollate broth

Question 6

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 7

A microbiologist is checking the mycobacteria cultures.She notices one tube of Lowenstein-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 8

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 9

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 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

All of these stains are used to visualize mycobacteria on a smear EXCEPT:

A) Ziehl-Neelsen
B) Kinyoun
C) Auramine
D) Acridine orange

Question 12

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 13

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

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

Question 14

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 are a buff color and exposure to light does not induce pigment formation
D) Species whose colonies fluoresce under ultraviolet light

Question 15

What is the optimum growth time for most mycobacteria associated with disease?

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

Question 16

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 are a buff color and exposure to light does not induce pigment formation
D) Species whose colonies fluoresce under ultraviolet light

Question 17

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) Lowenstein-Jensen (LJ)

Question 18

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 are a buff color and exposure to light does not induce pigment formation
D) Species whose colonies fluoresce under ultraviolet light

Question 19

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 20

What Mycobacterium species fails to grow in vitro?

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

Question 21

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) Rifampicin
D) Ciprofloxacin

Question 22

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

Question 24

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

A) Lymph nodes
B) Gastrointestinal
C) Genitourinary tract
D) Abdominal cavity

Question 25

What is the definition of a multidrug-resistant Mycobacterium tuberculosis?

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

Question 26

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 27

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 smears 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 28

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 29

A person travels to Mexico for a weeklong vacation.A couple weeks after returning come home,the person develops a cough,fatigue,weight loss,low-grade fever,and night sweats.What disease should the physician suspect?

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

Question 30

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

A) Niacin
B) Nitrate
C) Catalase
D) PYR

Question 31

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 32

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 33

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

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