Question 1

Quality control is performed to test the validity of catalase production at 68°C.M.fortuitum and M.tuberculosis are used,which yield a positive and negative reaction,respectively.Which one of the following statements explains this discrepancy?

Accepted Answer

A) Both organisms were most likely incubated at the wrong temperature. 
B) Both organisms were most likely incubated on the wrong media before testing. 
C) The catalase reagent is most likely expired. 
D) No discrepancy is present.M.fortuitum is catalase-positive and M.tuberculosis is catalase-negative at 68°C.

Question 2

Acid-fast smears should be examined carefully by scanning at least ________ oil immersion fields.

Accepted Answer

A) 100 
B) 200 
C) 300 
D) 400

Question 3

The stain that does not require heating the slide for better penetration of stain into the mycobacterial cell wall is known as the:

Accepted Answer

A) Kinyoun's. 
B) Ziehl-Neelsen. 
C) immunofluorochrome. 
D) carbolfuchsin.

Question 4

The 3-day test that is useful for identifying the rapid-growers,M.fortuitum and M.chelonae,and that measures the rate by which this enzyme breaks down phenolphthalein disulfate into phenolphthalein and other salts is the ____________ test.

Accepted Answer

A) niacin. 
B) phenolphthalein. 
C) arylsulfatase. 
D) Tween 80.

Question 5

The recent emergence of epidemic multidrug-resistant strains of M.tuberculosis,in conjunction with the end of the downward trend of reported cases of tuberculosis in the United States,has been largely attributed to:

Accepted Answer

A) human immunodeficiency virus (HIV)epidemic. 
B) ineffective treatment regimens. 
C) political factors. 
D) shortened treatment regimens.

Question 6

The most commonly isolated mycobacterium in the United States is:

Accepted Answer

A) M.tuberculosis. 
B) M.bovis. 
C) Mycobacterium avium-intracellulare. 
D) Mycobacterium paratuberculosis.

Question 7

Optimal conditions for most mycobacterial cultures are:

Accepted Answer

A) 25°C to 30°C in the dark in an atmosphere of 2% carbon dioxide (CO₂)and high humidity. 
B) 35°C in the dark in an atmosphere of 5% to 10% CO₂ and high humidity. 
C) 35°C in the dark in a microaerophilic atmosphere of 10% CO₂ and high humidity. 
D) 32°C in the dark in an atmosphere of decreased CO₂ and increased humidity.

Question 8

Characteristics that are found in the bacteria called Mycobacterium are:

Accepted Answer

A) a cell wall that contains N-glycolylmuramic acid and has a high lipid content. 
B) a cell wall that has a low lipid content. 
C) sensitive to decolorization by acidified alcohol. 
D) rapid-growers,as compared with most other human pathogenic bacteria.

Question 9

The nonpathogenic Mycobacterium commonly found in tap water,which has been a problem when tap water or deionized water has been used in the preparation of smears,is:

Accepted Answer

A) M.paratuberculosis. 
B) M.lepraemurium. 
C) M.phlei. 
D) M.gordonae.

Question 10

The Runyon system of classification is based on:

Accepted Answer

A) colonial and microscopic morphologic characteristics. 
B) biochemical characteristics. 
C) growth rate and colonial pigmentation. 
D) genotypic characteristics.

Question 11

Which of the following species of Mycobacterium causes a chronic disease of the skin,mucous membranes,and nerve tissue but has not yet been cultivated in vitro?

Accepted Answer

A) M.paratuberculosis 
B) M.lepraemurium 
C) M.phlei 
D) M.leprae

Question 12

Known to cause an inflammatory bowel disease referred to as Johne's disease in cattle,sheep,and goats,which organism has been isolated from the bowel mucosa of patients with Crohn disease?

Accepted Answer

A) M.paratuberculosis 
B) M.avium-intracellulare 
C) Mycobacterium phlei 
D) Mycobacterium lepraemurium

Question 13

In the identification of mycobacterial isolates,the niacin test involves the:

Accepted Answer

A) accumulation of niacin in the medium in which the organism is growing. 
B) metabolism of niacin to nicotinic acid by enzymatic action. 
C) testing of the isolate for susceptibility to niacin. 
D) utilization of niacin in metabolic pathways to produce nicotinic acid.

Question 14

The first test that is always performed on organisms growing on solid or liquid mycobacterial media is a(n):

Accepted Answer

A) niacin test. 
B) acid-fast stain. 
C) Gram stain. 
D) broth test.

Question 15

In the identification of mycobacterial isolates,the catalase test involves the:

Accepted Answer

A) breakdown of phenolphthalein disulfate into phenolphthalein and other salts. 
B) measurement of the height of a column of bubbles of oxygen. 
C) production of a lipase that is able to hydrolyze the catalase. 
D) development of a pink-to-red color,indicating a positive result.

Question 16

Under what circumstance might slow-growing mycobacteria appear to produce colonies in a few days?

Accepted Answer

A) When the inoculum is too heavy 
B) When subcultured to an enriched medium 
C) When incubated at slightly warmer temperatures 
D) When kept in the light

Question 17

Slow-growing NTM whose colonies produce no pigment,whether they are grown in the dark or the light,are referred to as:

Accepted Answer

A) scotochromogens. 
B) photochromogens. 
C) nonphotochromogens. 
D) chromogenicums.

Question 18

The specimens of choice for detecting nontuberculous mycobacterial disease are:

Accepted Answer

A) spontaneously produced sputa. 
B) gastric lavages. 
C) transtracheal aspirations. 
D) bronchial lavages,washings,and brushings.

Question 19

Slow-growing NTM whose colonies become pigmented when exposed to light are referred to as:

Accepted Answer