MICRO TEST 7 EXAM QUESTIONS AND ANSWERS
This sucks - CORRECT ANSWER✅✅:)
Mycobacteria:
air
motility
appearance - CORRECT ANSWER✅✅Aerobic, non-motile, non-spore forming thin bacilli
What type of cell wall does Mycobacteria have? - CORRECT ANSWER✅✅Acid-fast cell wall. Made of N-
glycolylmuramic acid. It is difficult to stain mainly due to high lipid content.
What is the stain for mycobacteria? What do they resist decoloring from? - CORRECT
ANSWER✅✅Carbolfuchsin or Auramine O. They resist decoloration with a 3% acidified solution of acid
alcohol
How fast do mycobacteria grow? - CORRECT ANSWER✅✅Very slowly because of their hydrophobic cell
surface
What are the two major groups of mycobacteria? - CORRECT ANSWER✅✅1. Mycobacterium
tuberculosis complex
2. NTM (non-tuberculous myco)
What is the primary cause of human tuberculosis? How many people around the world have it? -
CORRECT ANSWER✅✅Mycobacterium tuberculosis. 1.7 B people have it -- usually in unhealthy people.
What species are in the Mycobacterium tuberculosis complex? - CORRECT ANSWER✅✅M. tuberculosis,
bovis, and bovis BCG, africanum (rare in US)
What are the biochemical reactions for M. bovis and africanum? - CORRECT ANSWER✅✅Niacin -,
nitrate -
, What are the reactions for M. TB? What does it look like on a plate? - CORRECT ANSWER✅✅Nitrate +,
niacin +, catalase -.
Colonies are dry, rough, and appear 2-3 weeks at 35C
How much TB is required to cause infection? How many will develop disease? - CORRECT
ANSWER✅✅Inhaling ONE viable organism can lead to infection. 15-20% of people who become
infected develop the disease.
TB complex infection - CORRECT ANSWER✅✅1. T cells and macrophages migrate to the lungs,
organisms are phagocytized
2. organisms are capable of intracellular multiplication
3. granuloma forms in lungs
4. hypersensitivity causes necrosis.
What is latent TB? - CORRECT ANSWER✅✅Not infectious or active form of disease. They are dormant
and normally controlled by the immune system and do not cause disease or other TB symptoms
HIV and TB - CORRECT ANSWER✅✅Patients with HIV are more susceptible to TB. Co-infection common.
PPD skin test - CORRECT ANSWER✅✅used to ID people that have M. TB. PPD is injected and those that
have redness are positive
Quantiferon-TB gold - CORRECT ANSWER✅✅ELISA, measures a component of cell-mediated immune
reactivity to M. TB. Blood test
T-spot - CORRECT ANSWER✅✅Evaluates effector T cells, blood test.
How is TB transmitted? NTM? - CORRECT ANSWER✅✅TB is person to person. NTM is not person to
person, but through aerosols.
What are the four groups of NTM? - CORRECT ANSWER✅✅1. photochromogens
This sucks - CORRECT ANSWER✅✅:)
Mycobacteria:
air
motility
appearance - CORRECT ANSWER✅✅Aerobic, non-motile, non-spore forming thin bacilli
What type of cell wall does Mycobacteria have? - CORRECT ANSWER✅✅Acid-fast cell wall. Made of N-
glycolylmuramic acid. It is difficult to stain mainly due to high lipid content.
What is the stain for mycobacteria? What do they resist decoloring from? - CORRECT
ANSWER✅✅Carbolfuchsin or Auramine O. They resist decoloration with a 3% acidified solution of acid
alcohol
How fast do mycobacteria grow? - CORRECT ANSWER✅✅Very slowly because of their hydrophobic cell
surface
What are the two major groups of mycobacteria? - CORRECT ANSWER✅✅1. Mycobacterium
tuberculosis complex
2. NTM (non-tuberculous myco)
What is the primary cause of human tuberculosis? How many people around the world have it? -
CORRECT ANSWER✅✅Mycobacterium tuberculosis. 1.7 B people have it -- usually in unhealthy people.
What species are in the Mycobacterium tuberculosis complex? - CORRECT ANSWER✅✅M. tuberculosis,
bovis, and bovis BCG, africanum (rare in US)
What are the biochemical reactions for M. bovis and africanum? - CORRECT ANSWER✅✅Niacin -,
nitrate -
, What are the reactions for M. TB? What does it look like on a plate? - CORRECT ANSWER✅✅Nitrate +,
niacin +, catalase -.
Colonies are dry, rough, and appear 2-3 weeks at 35C
How much TB is required to cause infection? How many will develop disease? - CORRECT
ANSWER✅✅Inhaling ONE viable organism can lead to infection. 15-20% of people who become
infected develop the disease.
TB complex infection - CORRECT ANSWER✅✅1. T cells and macrophages migrate to the lungs,
organisms are phagocytized
2. organisms are capable of intracellular multiplication
3. granuloma forms in lungs
4. hypersensitivity causes necrosis.
What is latent TB? - CORRECT ANSWER✅✅Not infectious or active form of disease. They are dormant
and normally controlled by the immune system and do not cause disease or other TB symptoms
HIV and TB - CORRECT ANSWER✅✅Patients with HIV are more susceptible to TB. Co-infection common.
PPD skin test - CORRECT ANSWER✅✅used to ID people that have M. TB. PPD is injected and those that
have redness are positive
Quantiferon-TB gold - CORRECT ANSWER✅✅ELISA, measures a component of cell-mediated immune
reactivity to M. TB. Blood test
T-spot - CORRECT ANSWER✅✅Evaluates effector T cells, blood test.
How is TB transmitted? NTM? - CORRECT ANSWER✅✅TB is person to person. NTM is not person to
person, but through aerosols.
What are the four groups of NTM? - CORRECT ANSWER✅✅1. photochromogens
