Mycobacterium (laboratory diagnosis)

Question 1

These are the specimens of choice for detecting nontuberculous mycobacteria and other opportunistic pathogens in patients with immune dysfunction.

Answer 1

Bronchial washing/ bronchoalveolar lavage (BAL)

Question 2

It should be obtained in the morning after an overnight fast.

Answer 2

Gastric aspirates

Question 3

It is used to collect sputum from patients who may have swallowed sputum during the night.

Answer 3

Gastric lavage

Question 4

A first morning midstream specimen is preferred.

Answer 4

Urine

Question 5

(ml) urine collected in a sterile container.

Answer 5

15 - 40 ml

Question 6

Patients with AIDS, who may be at risk for developing disseminated mycobacterial disease resulting from Mycobacterium avium complex.

[specimen]

Answer 6

Stool

Question 7

for mycobacteremia.

[specimen]

Answer 7

Blood

Question 8

It is the best type of specimen for culturing of a skin lesion or wound.

Answer 8

aspirate

Question 9

It has been used for many years to determine an individual’s exposure to M. tuberculosis.

Answer 9

Tuberculin skin test

Question 10

Reactivity hours of skin testing.

Answer 10

48 hours

Question 11

The staining procedure involves the application of heat with the carbolfuchsin stain.

Answer 11

Ziehl-Neelsen

Question 12

Cold stain.

Answer 12

Kinyoun stains

Question 13

The screening procedure recommended for laboratories that have a fluorescent(ultraviolet) microscope.

Answer 13

Fluorochrome stain

Question 14

Enzyme-linked immunospot assay that requires isolation and incubation of peripheral blood mononuclear cells.(PBMCs)

Answer 14

T-SPOT-TB

Question 15

Assay measures the stimulation of T-cell interferon-gamma in whole blood in a tube precoated with M. tuberculosis antigens.

Answer 15

QuantiFERON Gold in tube

Question 16

It has the longest replication time, at 20 to 22 hours.

Answer 16

M.tuberculosis

Question 17

Mycobacterium that does not grow on media used routinely to isolate mycobacteria and requires extended incubation (6 to 8 weeks).

Answer 17

M.genavense

Question 18

Mycobacterium that fails to grow on artificial media.

Answer 18

M.leprae

Question 19

Selective media that contain antimicrobial agents, such as the Gruft modification of LJ and Mycobactosel are sometimes used in combination with nonselective media to increase the isolation of mycobacteria from contaminated specimens.

Answer 19

Egg-based media

Question 20

Serum albumin agar media, such as Middlebrook 7H10 and 7H11 agars.

Answer 20

Agar-based media

Question 21

Mycobacterium spp. grow more rapidly in liquid medium.`

Answer 21

Liquid media

Question 22

[2] Nonselective liquid media used for subculturing stock strains.

Answer 22

Middlebrook 7H9 broth and Dubos tween

Question 23

Colonies of this, are rough often exhibit a prominent patterned texture referred to as cording (curved strands of bacilli.

Answer 23

M. tuberculosis

Question 24

Colonies of this, have a variable appearance, with glossy whitish colonies often occurring with smaller translucent colonies.

Answer 24

Mycobacterium avium complex

Question 25

Rapid growers usually produce colonies within (how many days) after subculture.

Answer 25

3 to 4 days

Question 26

It is the most commonly used biochemical test for the identification of MTB.

Answer 26

Niacin Accumulation

Question 27

Mycobacterium that accumulates the largest amount of nicotinic acid.

Answer 27

M.tuberculosis

Question 28

A test differentiates M. tuberculosis from the scotochromogens and MAC.

Answer 28

Nitrate reduction

Question 29

It is is useful for differentiating species of photochromogens, nonchromogens, and scotochromogens.

Answer 29

Tween 80 hyrdrolysis

Question 30

It is most useful in distinguishing M. chelonae, which is generally negative.

Answer 30

Iron uptake

Question 31

Most members of the genus Mycobacterium possess the enzyme of this.

Answer 31

Arylsulfatase

Question 32

It is liberated with exposure to arylsulfatase.

Answer 32

Phenolphthalein

Question 33

[2] Exhibit activity with 14 days of incubation. [M.]

Answer 33

M. marinum M. szulgai

Question 34

It hydrolyzes pyrazinamide to pyrazinoic acid and ammonia in 4 days.

Answer 34

Pyrazinamidase

Question 35

Color pigment of pyrazinamidase.

Answer 35

Red

Question 36

Detection of this activity can be used to distinguish M. scrofulaceum, urease-positive, from M. gordonae, urease-negative.

Answer 36

Urease

Question 37

Color that indicates a positive reaction of urease.

Answer 37

pink to red

Question 38

Can grow on MacConkey agar without crystal violet, whereas most other mycobacteria cannot. [M.]

Answer 38

Mycobacterium fortuitum-chelonae

Question 39

It is susceptible to lower concentrations of T2H than MTB. [M.]

Answer 39

M. bovis

Question 40

It selectively inhibits the M. tuberculosis complex.

Answer 40

NAP

Question 41

Biosafety level for M. tuberculosis that propagated and manipulated.

Answer 41

Biosafety level 3

Question 42

Appear to be more commonly diagnostic than washing or biopsy.

Answer 42

Washing

Question 43

In Gastric lavage, serile water is instilled orally or via nasogastric tube aspiration. [ml]

Answer 43

30 to 60 ml

Question 44

Anticoagulants that may be used to inoculate cultures for the recovery of Mycobacterium spp. [3]

Answer 44

1. Sodium Polyanethol Sulfonate (SPS) 2. Heparin 3. Citrate

Question 45

[4] Decontaminating Agents

Answer 45

1. Sodium Hydroxide 2. N-Acetyl-L- cysteine 3. Benzalkonium Chloride 4. Oxalic Acid

Question 46

Usual concentration 2%, 3%, or 4%—serves as a digestant and decontaminating agent. [decontaminating agent]

Answer 46

Sodium hydroxide

Question 47

Treatment with mucolytic agents such as NALC splits mucoprotein, allowing greater sedimentation. [decontaminating agent]

Answer 47

N-Acetyl-L-cysteine

Question 48

It shortens the exposure time and effectively destroys many contaminants, with little bactericidal effect on the tubercle bacilli. [decontaminating agent]

Answer 48

Benzalkonium Chloride

Question 49

It is used to decontaminate specimens contaminated with Pseudomonas aeruginosa, such as sputum specimens from patients with Cystic fibrosis. [decontaminating agent]

Answer 49

Oxalic acid (5%)

Question 50

Contains 0.1% casein hydrolysate, which improves the recovery of isoniazid-resistant strains of M. tuberculosis

Answer 50

Middlebrook 7H11 medium