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Mycobactreria Flashcards

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1
Q

Leprosy is also called

A

Hansen disease

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2
Q

Leprosy (Hansen disease) is caused by

A

Mycobacterium leprae

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3
Q

Mycobacterium leprae - stracture

A

acid-fast bacillus

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4
Q

Mycobacterium leprae - reservoir in US

A

amradilos

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5
Q

Mycobacterium leprae - area of infection

A

it likes cool temperatures (infect skin and superficial nerves - glove and stocking loss of sensation

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6
Q

Mycobacterium leprae - in vitro

A

cannot grow

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7
Q

Leprosy (Hansen disease) - how many forms and which

A
  1. Lepromatous

2. Tuberciloid

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8
Q

Leprosy (Hansen disease) - lepromatous form - clinical manifestation

A

presents diffusely over the skin, with leonine (lion-like) facies, and is communicable

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9
Q

Leprosy (Hansen disease) - lepromatous form - immune system

A

low cell-mediated immunity with humoral Th2 response

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10
Q

Leprosy (Hansen disease) - Tuberciloid form - clinical manifestation

A

limited to few hypoesthetic. hairless skin plaques

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11
Q

Leprosy (Hansen disease) - Tuberciloid form - immune system

A

high cell-mediated immunity with a largely Th1 type response response

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12
Q

Leprosy (Hansen disease) - Treatment

A

dapsone with rifampin for tuberciloid dorm

clofazimin is added n lepromatous form

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13
Q

primary tuberculosis is caused by

A

infection with Mycobacterium tuberculosis of a Nonimmune host (usually host) (infection of previous unexposed individual)

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14
Q

secondary tuberculosis is caused by

A
  1. reinfection (infection with Mycobacterium tuberculosis of a partially immune hypersensitized host - usually adult)
  2. Reactivation due to immunosuppression
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15
Q

primary tuberculosis - lesion

A

Ghon complex: Hilar nodes + Ghon focus (calcified TB granuloma forming a nodule) usually in lower to middle lung

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16
Q

secondary tuberculosis after reactivation - lesion

A

fibrocaseous cavitary lesion (usually upper lobes)

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17
Q

Primary tuberulosis may lead to

A
  1. heals by fibrosis (immunity and hypersensitivity/PPD+)
  2. progressive lung disease (hiv/malnutrition)
  3. Miliary tuberulosis –> Death
  4. Preallergic lymphatic or hematogenous dissemination (dormant tubercle bacilli in several organs/reactivation in adult life)
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18
Q

Extrapulmonary tuberculosis - sites?

A
  1. CNS (parencymal tuberculoma or meningitis)
  2. Vertebral body (Pott disease)
  3. Lymphadenitis
  4. Renal
  5. GI
  6. Adrenals
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19
Q

Reactivation of tuberculosis in the lung lead to

A
  1. secodary tuberculosis fibrocaseous cavitary lesion (usually upper lobes)
  2. extrapulmonary tuberculosis
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20
Q

TB - primary tuberculosis occurs most commonly in

TB - secondary tuberculosis occurs most commonly in

A

1ry: children
2ry: adults

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21
Q

priamry tuberculosis - next step (and proportions)

A
  1. healing by fibrosis calcification (more than 90%)

2. Progressive 1ry tuberculosis esp on AIDS, malnutrition (less than 10%

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22
Q

Pott disease

A

tb in vertebral body

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23
Q

CNS TB?

A

parencymal tuberculoma or meningitis

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24
Q

TB - PDD positive if

A
  1. current infection or past exposure

2. false positive with BCG vaccination (further workup required)

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25
TB - PDD negative if
1. no infection 2. anergic (steroids, malnutrition, immunocompromised) 3. sarcoidosis
26
tests to diagnose TB
1. PPD | 2. Interferon-γ release assays (IGRA)
27
PPD vs Interferon-γ release assays (IGRA)
IGRA has fewer false positives from BCG vaccination
28
Mycobacteria - bugs?
1. Mycobacterium tuberculosis 2. Mycobacterium avium-intracellulare 3. Mycobacterium scrofulaceum 4. Mycobacterium marinum 5. Mycobacterium leprae
29
Mycobacterium tuberculosis - clinical manifestation
TB - fever, night sweats, weight loss, cough (non-productive or productive), hemoptysis
30
TB - cough - non-productive or productive?
both
31
Mycobacterium avium-intracellulare - causes
disseminated non-TB disease in AIDS
32
Mycobacterium avium-intracellularee - prophylaxis
azithromycin when CD+ cound under 50 | or rifabutin
33
Mycobacterium scrofulaceum causes
cervical lymphadenitis in children
34
Mycobacterium marinum causes
hand infection in aquarium handlers
35
Cord factor is found in
the cell wall of Mycobacterium (in virulent stains) --> creates a "serpentine cord" appearance in virulent M. tuberculosis
36
Cord factor - function
inhibits macrphage maturation and induces releases of TNF-α
37
Mycobacterium - Sulfatides?
surface glycolipids inhibit phagolysosomal fusion
38
Mycobacteria - bugs and diseases
1. Mycobacterium tuberculosis --> TB 2. Mycobacterium avium-intracellulare --> disseminated non-TB disease in AIDS 3. Mycobacterium scrofulaceum --> cervical lymphadenitis in children 4. Mycobacterium marinum --> hand infection in aquarium handlers 5. Mycobacterium leprae --> Leprosy (Hansen disease)
39
Ziehl-Neelsen (carbol fuschin) stains
Acid-Fast bacteria (Nocardia, Mycobaceria) and protozoa (Cryptosporidium oocysts)
40
mycobacteria - special characteristic of the structure (and clinical relevance)
cell wall are high in mycolic acid - detected by carbolfuchin in acid-fast stain
41
Special culture requirements - Mycobabterium Tuberculosis - media?
Lowenstein-Jensen agar
42
M. tuberculosis - prophylaxis and treatment
prophylaxis: isoniziad treatment: 1. rifampin 2. Isoniazid 3. Pyrazinamide 4. Ethambutol (RIPE)
43
M. intracellulare-avium - prophylaxis and treatment
prophylaxis: azithromycin, rifabutin treatment: Azithromycin or clarithromycin + ethambutol Can add rifabutin or ciprofroloxacin
44
M leprae - prophylaxis and treatment
prophylaxis: N/A treatment: Long-term treatment with dapsone and rifampin for tubrrculoid form. Add clofazimine for Lepromatous form
45
Antimycobacterial drugs - groups and drugs
1. Mycolic acid synthesis --> isoniazid 2. Arabinoglycan synthesis (Arabinosyl tranferase) --> ethambutol 3. mRNA synthesis (DNA-dependent RNA polymerase) --> Rifamycins (rifabutin, rifampin) 4. Intracellular (unclear mechanism) --> pyrazinamide 5. streptomycin
46
mycobacterial cell is composed by - from outer to inner
outer - acyl lipids, complex free lipids - mycolic acid - arabynogalactan - peptidoglycan - inner
47
Rifamycins - drugs and mechanism of action
Rifampin, rifabutin | inhibit DNA-dependent RNA polymerase
48
Rifamycins - drugs and clinical use
Rifampin, rifabutin 1. Mycobacterium tuberculosis treatment 2. Leprosy: delay resistance to dapsone 3. Meningicoccal prophylaxis 4. Chemoprophylaxis in contacts of children with H. influenzae type B 5. Can add in M. Avium-intracellulare (rifabutin) 6. M. Avium-intracellulare prophylaxis
49
Rifamycins - action on leprosy
delay resistance to dapsone
50
Rifamycins - toxicity
1. Minor hepatotoxicity 2. Drug interactions (increases cytochrome P-450) - esp rifampin 3. orange body fluids (nonhazardous side effect)
51
Rifamycins - drugs interaction by
increases cytochrome P-450 - esp rifampin
52
Rifamycins - HIV
RIfabutin favored over rifampin in HIV patients due to LESS cytochrome P-450 stimulation
53
Rifampin vs rifabutin according to side effects
Rifampin increases P450 much more than Rifabutin
54
Rifamycins - resistance
mutation reduce drug binding to RNA polymerase | --> monotherapy leads to resistance
55
Isonizid (INH) - mechanism of action / aka
Bacterial catalase peroxidase (encoded by KatG) needed to convert Isonizid (INH) to active metabolite --> decreases synthesis of mycolic acid. aka: INH
56
what is needed to convert Isonizid (INH) to active metabolite
Bacterial catalase peroxidase (encoded by KatG)
57
Isonizid (INH) - clinical use
1. Mycobaterium tuberculosis prophylaxis | 2. Mycobaterium tuberculosis treatment
58
Isonizid (INH) - resistance
Mutation leading to underexpression of KatG (bacterial catalase peroxidase)
59
bacterial catalase peroxidose is encoded by
KatG
60
Isonizid (INH) - toxicity
1. hepatotoxicity 2. P-450 inhibition 3. drug induced SLE 4. vitamin 6 - pyridoxine (B6) deficiency (--> peripheral neuropathy, siderblastic anemia)
61
Isonizid (INH) - solution of toxicity
vitamine 6 (Pyridoxine) can prevent neurotoxicity and anemia
62
Isoniazid - half-lives
different Isonizid (INH) half-lives in fast vs slow acetyators
63
Pyrazinamide - mechanism
mechanism uncertain Pyrazinamide is a prodrug that is converted to tha active compound pyrazinoic acid WORKS BEST at acidic ph (eg. in host phagolysosomes)
64
Pyrazinamide - active compound
pyrazinoic acid
65
Pyrazinamide - clinical use
treatment of Mycobacterium Tuberculosis
66
Pyrazinamide - toxicity
1. hyperuricemia | 2. hepatotoxicity
67
Ethambutol - mechanism of action
decreases carbohydrate polymerization of mycobacterium cell wall by blocking arabinosyltranferase
68
Ethambutol - clinical use
1. treatment of Mycobacterium Tuberculosis | 2. treatment of Mycobacterium acium-intracellulare
69
Ethambutol - toxicity
Optic neuropathy (red green color blindness)
70
M. tuberculosis and M.avium-intracellulare - prophylaxis and prevention
M. TUBERCULOSIS: prophylaxis: isonizid treatment: 1. rifampin 2. Isoniazid 3. Pyrazinamide 4. Ethambutol (RIPE) M. avium-intracellulae prophylaxis: azithromycin, rifabutin treatment: Azithromycin or clarithromycin + ethambutol Can add rifabutin or ciprofroloxacin
71
M leprae - prophylaxis and treatment
prophylaxis: N/A treatment: Long-term treatment with dapsone and rifampin for tubrrculoid form. Add clofazimine for Lepromatous form
72
TB - PDD positive if
1. current infection or past exposure | 2. false positive with BCG vaccination (further workup required)
73
TB - PDD negative if
1. no infection 2. anergic (steroids, malnutrition, immunocompromised) 3. sarcoidosis
74
Streptomycin - mechanism of action
inerferes with 30S compoment of ribosome
75
Streptomycin - clinical use
M. tuberculosis
76
Streptomycin - adverse effects
1. Tinnitus 2. Vertigo 3. ataxia 4. nephrotoxicity

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