TB

Question 1

What is the first step of acid fast staining?

Answer 1

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

Question 2

What is the second step of acid fast staining?

Answer 2

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

Question 3

What is the third step of acid fast staining?

Answer 3

Rise with water to stop decolorization

Question 4

What is the forth step of acid fast staining?

Answer 4

Counterstain with methylene blue for 30 seconds

Question 5

What is the fifth step of acid fast staining?

Answer 5

Rinse with water to remove excess methylene blue

Question 6

What is the sixth step of acid fast staining

Answer 6

Blot dry with bibulous paper and examine under oil immersion

Question 7

The 6 steps of acid fast staining

Answer 7

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

Question 8

What is M. tuberculosis resistant to?

Answer 8

Acid and alkali

Question 9

What are the structural components of M. tuberculosis?

Answer 9

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

Question 10

What component of M. Tuberculosis causes caseation necrosis?

Answer 10

Phosphatides

Question 11

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

Answer 11

Cord factor

Question 12

What component of M. Tuberculosis assists with lung pathogenesis?

Answer 12

Phtiocerol dimycocerosate

Question 13

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

Answer 13

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

Question 14

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

Answer 14

Measles
Varicella
Pertussis

Question 15

How do CD4 T cells help with TB?

Answer 15

Activate some infected macrophages to kill intracellular bacteria

Question 16

How do CD8 T cells help with TB?

Answer 16

Lyse other infected macrophages–> cause caseating granulomas

Question 17

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

Answer 17

TNF-alpha

Question 18

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

Answer 18

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

Question 19

Where do proliferative tuberculosis lesions develop

Answer 19

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

Question 20

Where do exudative tuberculosis lesions predominate?

Answer 20

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

Ghon complexes

Question 21

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

Answer 21

Immunosuppression

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

Question 22

What does a tuberculoma represent on CXR?

Answer 22

Old infection of TB

Question 23

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

Answer 23

Immunosuppression—no immune system to cause granulomas in the lungs

Question 24

How does TB scrofula differ in adults compared to children?

Answer 24

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

Question 25

What is TB scrofula?

Answer 25

Reactivation in lymph nodes

Painless, enlarging, or persistent mass with systemic symptoms including fever/chills, weight loss, or malaise

Question 26

What is suggestive of genitourinary TB?

Answer 26

Sterile pyuria

Question 27

What will the CSF look like in a pt with CNS TB?

Answer 27

Low glucose
Elevated protein
Slight pleocytosis

Question 28

What are the 2 main manifestations of Skeletal TB?

Answer 28

Arthritis of one joint

Pitt disease–spinal infection

• Back pain
• Stiffness
• Paralysis
• Lower extremities

Question 29

What is miliary TB

Answer 29

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

Question 30

Why are gastric aspirates used in lieu of sputum in children younger than 6 yrs?

Answer 30

Unable to cough forcefully enough to bring up sputum

Question 31

What is the important drug for TB tx?

Answer 31

Isoniazid

Question 32

What is the vaccine for TB?

Answer 32

Live attenuated M. Bovis

Question 33

What are the 2 strains of TB that are public health nightmares?

Answer 33

MDR and XDR

Question 34

An acid-fast + organism does what during the staining process?

Answer 34

hold carbolfuchsin during decolorization

Question 35

What is important for Tx of TB?

Answer 35

Begin with directly observed therapy with 4-plus drug courses that features isoniazid and isolate pt for 1st 2 weeks

Question 36

What are the most helpful factors for reducing incidence of TB in a pop?

Answer 36

Good diet and housing

Knowing that latent cases are not contagious