Exam 3 Mycobacteria Flashcards
(134 cards)
1
Q
Mycobacteria contain ____ in their cell wall
A
Mycolic acids
2
Q
Which Mycobacterial species cause chronic granulomatous diseases?
A
- Mycobacterium tuberculosis
- Mycobacterium leprae
- Mycobacterium bovis
3
Q
____ causes tuberculosis
A
Mycobacterium tuberculosis
4
Q
_____ causes leprosy/Hansen’s disease
A
Mycobacterium leprae
5
Q
Leprosy is now called:
A
Hansen’s Disease
6
Q
____ is transmitted via food and then by aerosol. It is identical to ____
A
M. bovis; Tuberculosis
7
Q
____ is a complex of 2 mycobacteria
A
Mycobacterium avium complex
8
Q
Mycobacteria must be stained using:
A
Acid fast (Ziehl-Neelsen) staining
9
Q
Acid fast bacteria have:
A
- mycolic acid
- fatty acids
- waxes
- complex lipids
10
Q
Acid fast staining method (4)
A
- Apply Carbolfuchsin (lipid soluble)
- Apply heat
- Decolorizer (acid alcohol) - does not affect acid fast bacteria
- Apply methylene blue counter stain (taken up by non-acid fast cells)
11
Q
Most Mycobacteria grow ____
A
Slowly
12
Q
____ cannot be cultured on bacteriological media
A
M. leprae
13
Q
Mycobacteria form ____ when cultured
A
Waxy colonies
14
Q
Worldwide, ____ is a common cause of infection related mortality
A
Tuberculosis
15
Q
TB is/is not common in the US
A
Not very common anymore, we no longer vaccinate for TB
16
Q
Highest rates of M. tuberculosis is among:
A
Non-US born
17
Q
Countries with highest rates of TB cases
A
- Mexico
- Philippines
- India
- Vietnam
- China
18
Q
Which US states have the highest rates of TB cases?
A
- California
- Texas
- New York
- Florida
have the most immigrants
19
Q
Tuberculosis is historically known by the names:
A
- Wasting disease
- Consumption
20
Q
Tuberculosis transmission
A
Respiratory - spread by airborne droplets (coughing, sneezing, speaking)
21
Q
Most people exposed to Tuberculosis do or do not become infected?
A
Do not become infected
22
Q
What are some susceptibility factors to contracting tuberculosis?
A
- overcrowding
- HIV infection
- Health care workers
23
Q
M. tuberculosis virulence factors
A
- Lipid coat
- Sulfatides
- Cording factor
24
Q
M. tuberculosis lipid coat is:
A
Antiphagocytic
25
M. tuberculosis sulfatides function
Glycolipids that inhibit phagolysosome formation, allows intracellular survival in macrophages
26
M. tuberculosis cording factor is derived from:
Mycolic acid
27
What do cording factors do?
Arrange M. tuberculosis cells into long and thin serpentine cord formation
28
Cording factors activate ____ which induces the formation of _____
Macrophages; granuloma
29
Granuloma
Masses of immune cells
30
3 primary infection outcomes of tuberculosis
1. Resolution
2. Latent infection
3. Progressive primary infection
31
Tuberculosis: Resolution
- also known as healing
- organisms are eliminated
- patient remains aymptomatic
32
Tuberculosis: Latent infection
- aka dormant
- Organisms in a dormant state within granuloma
33
Tuberculosis: Progressive primary infection
- Active TB
- Organism breaks out of granuloma and can infect another person via aerosol
34
Ghon (primary) complex
- lung lesions
- granuloma and mediastinal lymph node
35
Granuloma formation induces ____ response
CD4+ T-cell mediates (Th1)
36
Structure of granuloma - what is in it?
- M. tuberculosis organisms in the center
- surrounded by macrophages
- Th1 surrounds macrophages
- surrounded by fibroblasts
37
Giant cells are found in ____ and are formed by _____
granulomas; fused epithelioid cells
38
What are Epithelioid cells?
- End stage (unhealthy) macrophages
- activates macrophages that look like epithelial cells
39
TB granuloma center is ____
Necrotic/dead (caseous necrosis)
40
TB granuloma may undergo ____ and ____
necrosis (caseation) and cavitation
41
What stage of TB does granuloma form?
Can occur in any stage of TB
42
Latent TB is described as:
Presence of M. tuberculosis infection without signs and symptoms
43
Converters
Those whose M. tuberculosis skin/blood tests were previously negative but now positive
44
An example of a converter could be:
Health care workers
45
Active TB is more likely to occur in ____
Immune deficient patients (HIV/AIDS)
46
Active TB is usually localized to the _____ with ____ spread. This can lead to :
Lungs; local spread; systemic spread or miliary TB
47
Systemic spread of active TB can cause:
Pott's disease (bone)
48
Massive bacterial overload of active TB can lead to
Miliary TB (usually in immunocompromised subjects)
49
Miliary TB can spread to
Multiple organs (hematogenous spread)
50
Miliary TB usually occurs in
Compromised subjects
51
Miliary TB mortality
High
52
Tuberculosis clinical presentations
- persistent, productive cough
- Hemoptysis (bloody sputum)
53
TB meningitis (neurotuberculosis) presentation
- WBC: 25-500
- Cell type: Lymphocyte
- Glucose: Low
- Protein: High
54
Neurological TB can cause:
- Cranial nerve 6 palsy
- left eye complete ophthalmoplegia
55
Pott's disease affects
Spine (TB infection in the vertebrae)
56
________ is almost always secondary to pulmonary TB
Oral TB
57
TB diagnosis
- PPD skin test
- Acid fast stain of sputum, etc
- culture on Lowenstein-Jensen medium (8 weeks)
58
PPD test stands for:
tuberculin purified protein derivative
59
True or false: Acid fast stain of sputum shows many organisms
False - may be very few
60
Mantoux skin test
PPD (tuberculin) injected intradermally
61
PPD skin test measures degree of _____
Hypersensitivity to tuberculin
62
True or false: PPD skin test measures immunity to tuberculin
False - does not
63
PPD skin test is associated with _____ reaction
Delayed type hypersensitivity reaction (Th1)
64
During delayed-type hypersensitivity reaction, _____ cells are previously activated by APCs when antigen in the ____ is presented again. ____ cells activate ____ to cause an ____ response
Th1 helper T cells; PPD; Th1; macrophages; inflammatory
65
____ is measured 48-72 hours after PPD is injected
Induration
66
Induration is measured in ____, not:
mm; not negative or positive
67
Is there a correlation between induration size and current TB disease?
No
68
What does induration size correlate with?
Future risk of developing TB disease
69
Tuberculosis skin test - positive result for any person
>= 15 mm
70
Tuberculosis skin test - positive result for living or working in high risk social setting
>=10mm
71
Induration of____ is positive in HIV/AIDS patient
>= 5mm
72
TST interpretation for healthcare workers - baseline
>=10mm is a positive result
>= 5 mm if HCW has HIV
73
If you have gotten BCG vaccine, you may get:
False positive result on TST
74
False negative TST result may be due to
- anergy (inability to react to test)
- recent TB infection
- very young age (less than 6 mo)
- live virus vaccination if within 2 months (measles, smallpox)
- overwhelming TB infection
- incorrect administration of test
75
TST is done in ___ steps
2
76
Ability to react to tuberculin ___ over time
Decreases
77
First TST ____. Second TST is done ___ weeks later and may have ____ reaction
stimulates immune system; boosted or no reaction
78
True or false: blood testing can be done for TB
True - interferon-gamma release assays (IGRA)
79
IGRA blood testing for TB steps
- add M. tuberculosis antigens to blood sample
- IFN-gamma will be released if T cells are infected with M. tuberculosis
80
True or false: PCR can be used to test for M. tuberculosis
True - detects DNA + gene using sputum sample for resistance to rifampicin/rifampin
81
Latent TB - tx for subjects who convert to positive skin test/asymptomatic/clear chest xray
1 drug regimen - Isoniazid daily or twice weekly for 9 months
82
If Isoniazid can't be taken or INH-resistant TB:
Rifampin daily for 4 months
83
Active tuberculosis therapy
- Initial phase (first 8 weeks): 4 drugs used at same time (INH, RIF, ethambutol, pyrazinamide)
- Continuation phase: INH and RIF
84
True or false: there is antibiotic resistance associated with TB
True
85
Multidrug resistant TB (MDR-TB) is resistant to:
- INH
- Rifampin
86
MDR-TB is more common in:
- foreign-born US patients
- HIV-infected patients
87
Extensively drug resistant TB (XDR-TB) is resistant to:
Both first and second line drugs
88
How many high multi-drug resistant TB countries are there?
30
89
1 extensively drug resistant TB case cost ____ to treat
$568,000
90
Tuberculosis vaccine is called:
BCG vaccine (Bacille Calmette Guerin)
91
BCG vaccine is protective against:
Meningitis and disseminated TB in young children
92
BCG vaccine does not prevent:
Primary infection and latent pulmonary infection reactivation
93
Previous BCG vaccine can result in ____ PPD skin test
Positive
94
Treating a dental patient with latent TB requires:
Standard infection control precautions
95
If a patient comes in for dental treatment with active TB:
- defer elective treatment until patient is declared non-infectious
- urgent dental care done in airborne infection isolation
- dental team needs to use respiratory protection (fitted N95 mask)
96
___ of those exposed to tuberculosis results in infection
30%
97
TB is the one leading cause of: (2)
- opportunistic infection in HIV-infected patients
- cause of death in HIV/AIDS
98
____ is the strongest risk factor for progressing to TB disease and have an increased frequency of extrapulmonary infection
HIV infection
99
M. leprae is an acid-fast ____
Bacillus
100
M. leprae is endemic in:
Armadillos in TX and LA - same leprosy strain as in humans
101
M. leprae mode of transmission
Probably respiratory, direct contact with nasal discharge
102
Hansen's disease has ____ infectivity
Low - only 5% humans are susceptible
103
Hansen's disease - mode of attack
Attacks nerves - pts lose the ability to sense touch and pain
104
What are the major forms of Hansen's disease?
- Tuberculoid (mild form)
- Lepromatous (more severe)
105
Hansen's disease - tuberculoid form is associated with:
Good delayed-type hypersensitivity (Th1) response to bacterium
106
Hansen's disease - tuberculoid form has ___ organisms in lesions
Few (Paucibacillary)
107
Hansen's disease - lepromatous form is associated with:
Poor delayed-type hypersensitivity (Th2) response to bacterium
108
____ organisms are found in lesions of lepromatous form of Hansen's disease
Many
109
Hansen's disease, lepromatous form is a ____ disease
Severe, disfiguring
110
Another term for tuberculoid leprosy
Paucibacillary
111
Tuberculoid leprosy clinical presentations
- few localized, well circumscribed hypopigmented lesions
- anesthesia of affected skin due to dermal nerve involvement
112
Borderline lepromatous leprosy involves:
Scattered and generalized lesions (more severe)
113
Lepromatous leprosy clinical presentations
- numerous, hypopigmented, thickened skin lesions
- sensory nerve involvement beginning in the extremities
- tissue destruction, significant scarring
114
____ is commonly involved and becomes distorted with lepromatous leprosy
Face (leonine facies)
115
Collapsed nose bridge (saddle nose) can develop from
Lepromatous leprosy
116
Lepromatous leprosy can cause ____ lesions in up to 60%
Oral (tongue, palate)
117
Another term for lepromatous leprosy
Multibacillary
118
WHO recommends ___ regimens for leprosy treatment
Multidrug
119
Tuberculoid leprosy - treatment
rifampin and dapsone for 12 months
120
Lepromatous leprosy - treatment
Rifampin, dapsone, clofazimine for 24 months
121
M. bovis causes TB in:
Many mammals (ex, cattle, deer)
122
M. bovis is usually transmitted by:
2 steps
1. consumption of contaminated food (dairy products or meat)
2. then spreads by aerosol
123
___ is clinically identical to classical TB
M. bovis
124
M. bovis outbreak - pregnant mom acquired it from _____ in Mexico. Gave birth to twins prematurely at Summerlin hospital, mom died from TB meningitis. Then was spread by ___ from the ___ similarly to classical TB. Both newborn twins died
unpasteurized cheese; aerosol; infected twins
125
What species make up Mycobacterium avium complex?
| 2 species - complex
- Mycobacterium avium
- Mycobacterium intracellulair
126
Mycobacterium avium complex is also referred to as:
- Mycobacterium avium-intracellulair (MAI)
- Mycobacterium avium-intracellulair complex (MAC)
127
Mycobacterium avium complex is considered ____ mycobacteria
Non-TB; atypical
128
Mycobacterium avium complex is mainly ____ in humans
Opportunistic
129
How is Mycobacterium avium complex transmitted?
- inhalation of contaminated aerosols and dust
- ingestion
- direct inoculation
130
NTB Mycobacteria can cause infection in ___ and ____patients
immunocompetent and AIDS
131
Immunocompetent patients who contract MAC have ____ disease presentation
Chronic pulmonary
132
The most common mycobacterial infection in AIDS patients is:
Mycobacterium avium complex - typically cause disseminated diseases in AIDS patients
| AIDS-defining opportunistic infection
133
Mycobacterium avium complex is highly resistant to
Anti-TB drugs
134
Disseminated MAC can go to:
| examples
- jejunum
- brain lesions
