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MICBI Bacteria > Mycobacteria > Flashcards

Mycobacteria Flashcards

1
Q

What are the features of the Genus mycobacteria?

A
  • ZN stain -acid-fast
  • non-spore forming
  • non-motile
  • slow growing
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2
Q

Why does mycobacteria require specimen homogenization?

A

They are slow growing, thus requires decontamination step to kill other bacteria first before culturing using NaOH

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3
Q

How can we distinguish M. tuberculosis from M. leprae?

A

M. tuberculosis is heat-sensitive catalase +ve

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4
Q

State the transmission of M. tuberculosis.

A

Air borne

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5
Q

Pathogenesis of M. tuberculosis depends on host immunity. Briefly explain why.

A
  1. Host immunity +ve: no disease, chronic inflammation (granuloma with central necrosis, bacteria dormant but viable)
  2. Host immunive -ve: reactivation, present in any organ
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6
Q

Which of the following about M. Tuberculosis is correct?
A. it is facultative intracellular, which persists in macrophages
B. it is an obligate aerobe
C. It can spread from lungs to hilar LN and even other organs via blood
D. It can be grown quickly on LJ medium
E. Tuberculin test- PPD 2TU ID is used as diagnosis, zone of skin induration is measured.

A

All except D

  • Acid fast bacteria culture: LJ medium, but slow-growing (4-6 weeks), faster with radiometric substrate
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7
Q

List the possible symptoms of primary pulmonary TB.

A
  1. Asymptomatic
  2. Constitutional Sx (fever, night sweats, fatigue, weight loss)
  3. Pulmonary Sx (cough, sputum, hemoptysis)
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8
Q

What does it mean by secondary pulmonary TB?

A

Due to temporary weakening of CMI (cell-mediated immunity), it may disseminate to any other organs (miliary TB) with poor prognosis

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9
Q

What is tuberculoma?

A
  • Tuberculoma/ Tuberculous meningitis: CNS cavity lesion
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10
Q

What are the possible manesfistations of secondary TB in lymphatics?

A
  1. Tuberculosis lymphadenitis (scrofula): MC non-pulmonary TB, usually involves cervical LN
  2. TB peritonitis: due to rupture of caseous abdominal LN
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11
Q

What is the disease related to skeletal system in secondary pulmonary TB? Which part of the skeletal system is damaged?

A

Pott’s disease affected thoracic and lumbar spine (demineralization vertebral bodies)

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12
Q

What can be the treatment for M. tuberculosis infection?

A 
RIPE:
R: rifampin
I: Isoniazid
P: Pyrazinamide 先啊咪
E: Ethambutol
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13
Q

What are the preventive medicine for M. tuberculosis?

A
  • BCG vaccine

- Rifampicin and isoniazid for latent TB

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14
Q

Which of the following about M.leprae are correct?
A. It is an obligate intracellular
B.It’s optimal growth is similar to human body temperature
C. It is transmitted by nasal discharge or prolonged contact
D. It’s pathogenesis involve peripheral nerves more than central nerves

A

All except B

B: should be less than body temperature (27-30 degrees)

D: Cooler parts of the body - skin, peripheral nerves, extremities

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15
Q

What are the test results (2 forms of leprosy) of M. leprae in Lepromin skin test ?

A

+ve in tuberculoid form

-ve in lepromatous form

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16
Q

What are the 2 forms of leprosy and what are their differences in terms of CMI?

A
  1. Tubercoloid (TL)
    - Strong, Th1 mediated
  2. Lepromatous (LL)
    - weak Th2 mediated
17
Q

What are the differences between tuberculoid and lepromatous leprosy in terms of

  1. Organism in tissue
  2. Damage origin
  3. Treatment duration
  4. Hypopigmentation
A

TL

  • Low amount of organism in tissue
  • damage origin is CMI > non-ceseasting granuloma formation
  • Treatment: 6 months
  • marked hypopigmentation

LL

  • high amount of organism in tissue
  • damage origin: overgrowth of bacteria
  • Treatment: more than 2 years
  • little hypopigmentation
18
Q

What are the characteristic clinincal charateristics in both TL and LL together? (4)

A
  1. Nerve: sensory loss, paralysis
  2. Skin: thickening, nodular appearance, leonine facies
  3. Bone: resorption and shortening of digits
  4. Muscle wasting
19
Q

What are the treatment for leprosy?

A
  1. Dapsone
  2. Rifampin
    (+3. clofazimine for LL)
20
Q

How is Mycobacteria other than tuberculosis (MOTT) classified?

A

Runyon group: classified bsed on ability to produce pigment and growth rate

  • it is non-contagious
21
Q

M. avium complex (MAC) and M.kansasii are commonly presented in which types of patient?

A
  1. with pre-existing pulmonary diease

2. immunocompromised patients

22
Q

Which types of MOTT are associaed with bone/joint/soft tissue infection after trauma?

A

M. fortuitum and 課頹tum

M. chelonae “ke”攞黎

23
Q

Which type of MOTT causes pulmonary infection which is clinically indistinguishible from TB but not airborne transmitted?

A

MAC (M.avium complex) and M. kansasii

24
Q

What disease is M. scrofulaceum associated with?

A

Cervical lymphadenitis (scrofula) in children

25
Q

What diseases is M. marinum associated with?

A

Superficial skin lesions - fisherman’s granuloma

MICBI Bacteria (7 decks)

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