Medical Microbiology: Mycobacteria MCQ

Multiple Choice Question on Mycobacteria tuberculosis and Mycobacteria leprae

1) Mycobacteria are acid-fast positive bacteria because of:
a) the presence of lipopolysaccharide in the bacterial cell wall
b) the presence of mycolic acid in the bacterial cell wall
c) the presence of lipids
d) Both B and C options given above

2) Which of the following first-line antibiotics are usually resistant to Mycobacterium tuberculosis?
a) Isoniazid and ciprofloxacin
b) Isoniazid and Rifampin
c) Rifampin and ciprofloxacin
d) Rifampin and streptomycin

3) What is the mechanism responsible for antibiotic resistance in Mycobacterium tuberculosis?
a) Mutations in DNA gyrase gene
b) Alterations in beta-lactamase
c) Mutations in the catalase-peroxidase gene
d) Alterations in RNA polymerase


4) All of the following are the examples of selective media used for culture of Mycobacterium tuberculosis, except?
a) Inspissated egg media
b) Middlebrook 7H10/7H11 media with antibiotics
c) Dubos media
d) Middlebrook 7H10 media without antibiotics

5) Which of the following statement is true about the tuberculin test and purified protein derivative (PPD)?
a) The presence of intradermal skin induration is observed in 6 to 8 hours after being applied
b) The redness of skin or erythema is also measured while reading the tuberculin test
c) A positive tuberculin test means that a person was infected with M. tuberculosis in the past and continues to carry the viable organism
d) A positive PPD test indicates that a person can never be infected with M. tuberculosis

6) Which of the following is fast growing, non-chromogenic rod bacilli?
a) Mycobacterium ulcerans
b) Mycobacterium avium complex
c) Mycobacterium leprae
d) Mycobacterium fortuitum

7) All of the following are the symptoms of pulmonary tuberculosis, EXCEPT?
a) Weakness and fatigue
b) Decreased body temperature
c) Weight loss
d) Severe prolonged cough with sputum or blood

8) Which of these following categories of people do not require the test for TB infection?
a) A 30 years old man traveling from India to the USA for the first time
b) A 45 years old woman contradicted with HIV infection
c) A 7 years old healthy girl living together with her grandmother who has tuberculosis infection
d) None of the above

9) Which of the following bacteria causes lung infection and is the most common non-tuberculous mycobacterial infection associated with AIDS patients?
a) Mycobacterium avium complex
b) Mycobacterium leprae
c) Mycobacterium gordonae
d) Mycobacterium gastri

10) A 40 years old patient who has clinical symptoms pulmonary tuberculosis for the past two months. The chest x-ray examination revealed a typical feature of tuberculosis infection. A photochromogenic (orange pigment when exposed to UV light) acid-fast rod bacterium was isolated from the sputum sample. The identified bacteria is:
a) Mycobacterium avium
b) Mycobacterium tuberculosis
c) Mycobacterium kansasii
d) Mycobacterium leprae


11) All of the given are the distinguishing characteristics of Mycobacterium leprae, EXCEPT:
a) Acid-fast bacilli
b) cannot be isolated by in-vitro culture method
c) is a human and as well as animal pathogen
d) can be isolated by in-vivo culture method

12) Which one of the following acid-fast rod bacilli can take up to ten years for its growth in host cells and causes skin infections?
a) Mycobacterium tuberculosis
b) Mycobacterium avium complex
c) Mycobacterium leprae
d) Nocardia spp

13) Other than Mycobacterium tuberculosis which of the given bacteria causes tuberculosis infection in animals and can be transmitted to human by consumption of milk and other animal products?
a) Mycobacterium ulcerans
b) Mycobacterium leprae
c) Mycobacterium bovis
d) Mycobacterium abscessus

14) The treatment regimen for initial therapy of tuberculosis caused by M. tuberculosis includes?
a) Streptomycin and rifampin
b) Isoniazid, streptomycin, and ethambutol
c) Rifampin, isoniazid, and ciprofloxacin
d) Isoniazid, rifampin, pyrazinamide, and ethambutol

15) What is the interferon-gamma release assay?
a) The antigen detection test for the Mycobacterium spp
b) The DNA detection test in Mycobacterium spp
c) The test used as an alternative tuberculin skin test in latent tuberculosis
d) The test used as an alternative tuberculin skin test in active tuberculosis


Multiple Choice Answers Review
1-d) Both B and C options given above
2-b) Isoniazid and Rifampin
3-c) Mutations in the catalase-peroxidase gene
4-d) Middlebrook 7H10 media without antibiotics
5-c) A positive tuberculin test means that a person was infected with M. tuberculosis in the past and continues to carry the viable organism
6- d) Mycobacterium fortuitum
7- b) Decreased body temperature
8- d) None of the above 9-a) Mycobacterium avium
10-c) Mycobacterium kansasi
11-c) is a human and as well as animal pathogen
12-c) Mycobacterium leprae
13-c) Mycobacterium bovis
14-d) Isoniazid, rifampin, pyrazinamide, and ethambutol
15-a) The antigen detection test for the Mycobacterium spp

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