TB Flashcards

1
Q

What is the first step of acid fast staining?

A

Cover smear with carbolfuchsin and stem over boiling water for 8 mins

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2
Q

What is the second step of acid fast staining?

A

After slide has cooled decolorize with acid-etoh for 15-20 seconds

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3
Q

What is the third step of acid fast staining?

A

Rise with water to stop decolorization

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4
Q

What is the forth step of acid fast staining?

A

Counterstain with methylene blue for 30 seconds

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5
Q

What is the fifth step of acid fast staining?

A

Rinse with water to remove excess methylene blue

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6
Q

What is the sixth step of acid fast staining

A

Blot dry with bibulous paper and examine under oil immersion

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7
Q

The 6 steps of acid fast staining

A
Carbolfuschsin with steam
Decolorize with acid-etoh
Rinse with water
Counterstain with methylene blue
Rinse with water
Dry with bibulous paper and examine under oil immersion
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8
Q

What is M. tuberculosis resistant to?

A

Acid and alkali

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9
Q

What are the structural components of M. tuberculosis?

A

Mycelia acids
Wax D
Phosphatides–caseation necrosis
Cord factor–virulence–microscopic serpentine appearance
Phtiocerol dimycocerosate–lung pathogenesis

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10
Q

What component of M. Tuberculosis causes caseation necrosis?

A

Phosphatides

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11
Q

What component of M. tuberculosis gives its microscopic serpentine appearance?

A

Cord factor

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12
Q

What component of M. Tuberculosis assists with lung pathogenesis?

A

Phtiocerol dimycocerosate

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13
Q

How does TB travel throughout the body and get to extra pulmonary sites?

A

Proliferates within mononuclear phagocytes (macrophages) and establish latency in immunocompetent ind.

Lymph nodes
Kidney
Bones
Meninges

Lungs–infected by inhaling droplets

GI–infected by swallowing infected sputum

Kidney –infected from hematogenous spread of bacilli

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14
Q

What are the non-TB infections that can activate quiescent TB?

A

Measles
Varicella
Pertussis

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15
Q

How do CD4 T cells help with TB?

A

Activate some infected macrophages to kill intracellular bacteria

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16
Q

How do CD8 T cells help with TB?

A

Lyse other infected macrophages–> cause caseating granulomas

17
Q

What cytokine has an important role in maintaining latency of TB?

18
Q

What is a Ghon complex, how is it formed and what does it cause?

A

Formed by bacilli proliferation lovely and spreading through the lymphatics to the hilar nodes–Ghon complex forms

Hon complex allows the bacilli to get into the bloodstream

19
Q

Where do proliferative tuberculosis lesions develop

A

Where the bacillary load is small and host cellular-immune responses dominate

20
Q

Where do exudative tuberculosis lesions predominate?

A

When large numbers of bacilli are present and host defenses are weak

Ghon complexes

21
Q

What are the risk factors for poor outcome with TB infection?

A

Immunosuppression

  • Uncontrolled HIV–inadequate HAART
  • Steroids
  • IFNg deficiency
  • THF-a antagonists
  • Age
22
Q

What does a tuberculoma represent on CXR?

A

Old infection of TB

23
Q

Why would an HIV+ pts CXR be normal even if they are known to have a TB infection?

A

Immunosuppression—no immune system to cause granulomas in the lungs

24
Q

How does TB scrofula differ in adults compared to children?

A

Adults–95% of mycobacterial cervical infections caused by tuberculosis

Children–92% of cases due to atypical mycobacterium—which are acquired by putting contaminated objects in their mouths

25
What is TB scrofula?
Reactivation in lymph nodes Painless, enlarging, or persistent mass with systemic symptoms including fever/chills, weight loss, or malaise
26
What is suggestive of genitourinary TB?
Sterile pyuria
27
What will the CSF look like in a pt with CNS TB?
Low glucose Elevated protein Slight pleocytosis
28
What are the 2 main manifestations of Skeletal TB?
Arthritis of one joint Pitt disease--spinal infection - Back pain - Stiffness - Paralysis - Lower extremities
29
What is miliary TB
Hematogenous spread of TB throughout the body Many tiny non calcified foci of infection appear "like millet seeds" in lung on CXR Most likely to develop right after primary infection highest risk in very young and old Fatal if untreated
30
Why are gastric aspirates used in lieu of sputum in children younger than 6 yrs?
Unable to cough forcefully enough to bring up sputum
31
What is the important drug for TB tx?
Isoniazid
32
What is the vaccine for TB?
Live attenuated M. Bovis
33
What are the 2 strains of TB that are public health nightmares?
MDR and XDR
34
An acid-fast + organism does what during the staining process?
hold carbolfuchsin during decolorization
35
What is important for Tx of TB?
Begin with directly observed therapy with 4-plus drug courses that features isoniazid and isolate pt for 1st 2 weeks
36
What are the most helpful factors for reducing incidence of TB in a pop?
Good diet and housing Knowing that latent cases are not contagious