QuestionSBA
QuestionChoice
Tissue culture involves growing cells and inoculating them with infectious organisms to investigate organism growth. Although *Mycobacterium tuberculosis* culture is available, the process itself may take 4-8 weeks and thus is not used routinely for diagnostic purposes.
10004773
c
Tissue culture
QuestionChoice
*Mycobacterium tuberculosis* is the causative organism of tuberculosis. They have a very thick lipid-rich wall, so Gram staining is not helpful for investigation. Thus, for direct microscopy, a special stain called the Ziehl-Neelsen stain is used to visualise the mycobacteria.
10004771
a
Ziehl Neelsen stain
QuestionChoice
Light microscopy is not sensitive enough for *Mycobacterium tuberculosis* visualisation. The preferred method is fluorescence microscopy, commonly done with auramine staining.
10004775
e
Light microscopy
QuestionChoice
Plaque assays are an investigation used for counting viruses in a certain sample. A monolayer of cells is grown, and a set amount of sample is diluted. A plaque, which is an area of cell destruction becomes visible, and the concentration of virus particles in the original sample is inferred. *Mycobacterium tuberculosis* is not a virus, it is a bacteria.
10004774
d
Plaque assay
QuestionChoice
Gram stain classifies bacteria by the colour they stain which reflects certain bacterial properties (differences in cell wall composition and embedded proteins). *Mycobacterium tuberculosis* is not truly Gram-positive or negative, and so this type of stain is not sensitive enough for this class of organism.
10004772
b
Gram stain
Concept
Chapter
2693
4331
Tuberculosis
Topic
194
Infectious Diseases
13501
Which of the following laboratory techniques is the best confirmatory diagnostic investigation for Mycobacterium tuberculosis?
a