An acid-fast bacillus is recovered from a bronchial washing on Lowenstein-Jensen medium after 18 days at 35°C with CO2. Initially the colonies are buff, raised, and rough when grown in the dark. After exposure to light, no change in pigmentation is noted. On examination at 10X magnification, the colonies reveal serpentine cording. Which of the following biochemical test reactions will confirm the identity of the most likely etiologic agent?
A) Niacin and nitrate negative
B) Niacin and nitrate positive
C) Niacin positive and nitrate negative
D) Niacin negative and nitrate positive
Correct Answer:
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Q3: All of the following statements are true
Q4: Infections due to tubercle bacilli are
A) typically
Q5: If a slow-growing, acid-fast bacillus is able
Q6: Mycobacterium fortuitum is classified as a
A) photochromogen.
B)
Q7: Mycobacterium tuberculosis is classified as a
A) photochromogen.
B)
Q9: A slow-growing, acid-fast bacillus provides the following
Q10: The acid-fast colonies in the image provided
Q11: The presence of acid-fast bacilli in a
Q12: A skin lesion grows an acid-fast bacilli
Q13: A sputum, submitted for AFB culture and
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