Question
The micro-organism shown in the photomicrograph below grows in L.Jmedia in how much time?
A. 1 0- 14 days.
B. 2-3 weeks.
C. 4-8 weeks.
D. > 10 weeks.
Show Answer
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Correct Answer » C
Explanation
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Ans:C. 4-8 weeks.
The micro-organism shown in the photomicrograph above represents M tuberculosis(Acid Fast stain)
- M tuberculosis produces visible colonies on solid media (L.J. media) in 4-8 weeks.
The Löwenstein–Jensen medium,( LJ medium),is a growth medium specially used for culture of Mycobacterium species, notably Mycobacterium tuberculosis.
- When grown on LJ medium, M. tuberculosis appears as brown, granular colonies (sometimes called “buff, rough and tough”). The medium must be incubated for a significant length of time,4-8 weeks,due to the slow doubling time of M. tuberculosis (15–20 hours) compared with other bacteria.
- Use of liquid media with radiomimetric growth detection (BACTEC-460) and the identification of isolates by nucleic acid probes give result in 2-3 weeks.
