Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Pulm > Micro - TB > Flashcards

Micro - TB Flashcards

1
Q

4 mycobacteria strains and their reservoirs

A
  1. M. bovis - cows
  2. M. avium - AIDS pts
  3. M. tuberculosis - humans
  4. M. leprae - humans?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Presentation of M. bovis

A

Extrapulmonary TB in someone exposed to unpasteurized milk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Presentation of M. avium

A

TB-like dz in AIDS pt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

M. tuberculosis is the leading cause of:

A

Death by bacterial infectious disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How many people affected by TB worldwide?

A

1/3 of population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

White plague v. black plague

A

White plague - TB

Black plague - Yersinia pestis (subcutaneous hemorrhage)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

MTB is (aerobic, anaerobic) (intracellular, extracellular) (shape)

A

Aerobic, facultative aerobe, large rod

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where do mycobacteria normally reside in body?

A

Dry, oily areas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Virulence factors of MTB

A
  1. Facultative intracellular parasite
  2. Obligate aerobe
  3. Peptidoglycan + lots of lipoproteins
  4. Binds to mannose, complement, and Fc receptors of macrophages
  5. Inhibit phagosome-lysosome fusion
  6. Decreased oxidative toxicity of macrophages
  7. Antigen 85
  8. Slow generating
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does being a facultative intracellular parasite contribute to MTB virulence?

A

Avoids Ab/complement toxicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does being an obligate aerobe contribute to MTB virulence?

A

Can live in upper lobes of lungs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does having peptidoglycan + lots of lipoproteins contribute to MTB virulence?

A 
Antibiotic resistance
Resistance to complement lysis
Resistance to stains
Resistance to acid or base compounds
Can live in macrophages
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does binding to mannose, complement, and Fc receptors of macrophages contribute to MTB virulence?

A

Allows cell entry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is antigen 85 and how does it contribute to MTB virulence?

A

Group of proteins secreted by MTB that bind fibronectin and wall off the bacteria from immune cells + facilitate tubercle formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does the slow generation of TB contribute to virulence of MTB?

A

Can grow under the radar of immune cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Characteristic of MTB culture

A

Serpentine cord colonies due to cord factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Only virulent strains of MTB produce:

A

Cord factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Characteristic of MTB gram stain

A

Ghost cells - mycolic acid repels the stain, causing cleared areas that resemble empty cells/ghosts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Name of acid-fast technique? How does it work?

A

Ziehl-Neelsen stain

Stain with carbolfuschin (pink dye) then decolorized with acid; holds “fast” to the pink stain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

3 lipid proteins of MTB cell wall

A
  1. Mycolic acid
  2. Wax D
  3. Cord factor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

To which MTB lipoprotein does carbolfuschin bind?

A

Mycolic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the function of mycolic acid?

A

Reduces permeability of MTB to ROS of macrophages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the function of cord factor?

A

2 mycolic acids + disaccharide that allows parallel growth of MTB (serpentine colonies) and inhibits PMN migration and complement deposition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the function of wax D?

A

Part of lipid envelope; major component of Freund’s complete adjuvant (solution used to boost immunity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
TB infection vs. disease
``` Infection = immune system controlling MTB Disease = immune system unable to control MTB ```
26
When is MTB contagious?
During disease!!
27
How does immune system control MTB?
Surrounds tubercles with macrophages, forming a hard shell that keeps MTB from spreading
28
#1 predisposing factor for MTB
HIV
29
___% of people exposed with TB get infected | ___% of people infected with TB get disease
25% | 10%
30
___% of AIDS patients have TB
10% (400x general population)
31
(T/F): Most people infected with TB progress through stage 5 of the disease
False - only 10% infected develop disease, and only a small % of those will progress to stage 5
32
Stage 1
Inhaled MTB taken up by alveolar macrophages
33
Most infective droplet nuclei?
5 micrometers
34
Nuclei droplet contain ~ ___ TB
3
35
What happens to large droplet nuclei?
Deposit in URT where they do not cause infection
36
Stage 2
MTB replicates in alveolar macrophages but they're inactive so they can't kill MTB; additional inactive macrophages recruited; can spread to lymph nodes via macrophages
37
Time course of stage 2
Begins 7-21 days after infection
38
Stage 3
Cell-mediated response T cells release IFy --> activate macrophages --> destroy TB --> macrophages release lytic factors that cause tissue damage and tubercle formation
39
Time course of stage 3? Significance?
6-10 weeks post infection | This is when skin test will be +; must re-test pt 2 months later if skin test -
40
What is a tubercle?
Caseating granuloma lined by macrophages; MTB can't multiply within these granulomas due to low pH and anoxic environment but they persist there
41
Stage 4
Inactivated macrophages recruited by MTB for replication --> tubercle grows --> can spread to bronchus or blood vessel --> miliary TB
42
Two types of lesions in milliary TB
1. Exudative - PMNs surround MTB and they replicate without restriction = soft tubercle 2. Productive or granulomatous - host becomes hypersensitive to tuberculoproteins = hard tubercle
43
Stage 5
Center of tubercle caseates/liquifies which is conducive to MTB growth --> MTB grows extracellularly --> invades bronchus --> bronchus necrosis --> cavity and spread of MTB
44
Two routes cavity can take:
1. Heals and undergoes calcified fibrosis --> Gohn complex | 2. Small metastatic foci heal and undergo calcified fibrosis --> Simon foci
45
How do Gohn complex/Simon foci lead to reactivation?
Contain viable MTB
46
When is TB considered MDR TB?
Resistant to 2+ Abx
47
Typical regimen for TB and duration of tx?
RIPE (rifampin, isoniazid, pyrazinamide, ethambutol) | 6-9 months
48
Who would you expect to see XDR TB in?
HIV Foreign-born Reactivation TB
49
Ways to diagnose TB
1. PPD skin test 2. Acid-fast stain 3. CXR 4. Culture
50
How does PPD skin test work?
Inject pt with purified protein derivative (PPD; usually tuberculin); if macrophages have been activated, you will get a red welt
51
How long do you wait before reading TB skin test?
72 hours
52
What would you see on CXR of primary TB?
Pleural effusion of any lobe + lymphadenopathy
53
What would you see on CXR of reactivated TB?
Consolidation in upper lobe only + cavitations
54
What would you see on CXR of milliary TB?
Caseating granulomas
55
What is difficult about culture of MTB from sputum?
Slow growing so takes up to 4 weeks for dx; Abx resistance testing can take additional time
56
Why might someone born outside US have + PPD?
Vaccinated or exposed to TB
57
Could someone have a true + PPD without having MTB?
Yes - could have another strain of mycobacterium
58
Why must you never give only a single agent in tx of TB?
Development of resistance; must give at least 4
59
Name of TB vaccine? Type?
BCG | Live attenuated M. bovis
60
Why don't we give BCG in US?
1. Makes PPD ineffective 2. Can't circumvent disease reactivation 3. It can't prevent infection, only disease

Pulm (33 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions