Tuberculosis

Question 1

HIV and TB interact to result in a:

Answer 1

syndemic

Question 2

Four qualities of Mycobacterium tuberculosis?

Answer 2

1) Obligate aerobe
2) Grows slowly (13 hr generation time)
3) Resistant to chemicals and drying
4) Acid-fast (like nocardia!)

Question 3

Would a gram stain work with Mycobacterium tuberculosis?

Answer 3

No - use an acid fast stain.

Question 4

Mycobacterium tuberculosis sticks together and attach to one another - this is called:

Answer 4

cording - this is the reason why we have granulomas in TB!

Question 5

What is the specific agent that is responsible for the granuloma of TB?

Answer 5

Mycolic acid (specifically 66-dimycolate)

Question 6

Discuss some general characteristics of “TUBErculosis”.

Answer 6

Like TUBES:

• Have strong cell wall with lipids and waxes (need acid-fast stain)
• Obligate aerobes (tubes have openings at ends for “air”)
• They grow slowly
• Undergo cording

Question 7

The waxy coats on the surface of TB are made of:

Answer 7

beta-hydroxy acids

*resistant to phagocytosis, drying, and germicides. Heating works best!

Question 8

What are the two components of the cell envelope in TB that block phagocytosis?

Answer 8

PIM and Lipoarabinomannan (LAM)

Question 9

Of 50 normal students that are infected with TB, what percent will have a latent infection, and what perfect will have primary infection (bad one with coughing blood, etc.)?

Answer 9

95% = latent
5% = infected immediately

Question 10

Of the 95% latently affected individuals, 10% are at ___ risk for getting secondary TB.

Answer 10

lifetime

Question 11

Of the 95% latently affected HIV individuals, 10% are at ___ risk for getting secondary TB.

Answer 11

annual

Question 12

What are the drugs in the strict, 4-drug treatment of TB?

Answer 12

(RIPE)
RIF
INH
PZA
EMB

Question 13

When the Mtb gets eaten by macrophage, what does it do to avoid being killed? (3)

Answer 13

• inhibits lysosome fusion
• inhibits pH drop
• stimulates chemokine

Question 14

The granuloma that forms in TB functions in:

Answer 14

limiting the spread of TB; keeps the organism trapped in there.

The granuloma center = caseous and necrotic; eventually become calcified

Question 15

The granuloma that forms in TB has a central mass composed of what cell types?

Answer 15

Macrophages
Epithelial cells
Giant cells (Langhan cells)
Lymphocytes

Question 16

What is the Gohn complex?

Answer 16

Characteristic; In most TB-infected people, the granuloma eventually stops growing and decreases in size/calcifies.

Question 17

The central mass in granuloma is encapsulated by:

Answer 17

fibrin

Question 18

What are the three defensive body strategies against TB?

Answer 18

1) Activated macrophages
2) Walling off via calcification and fibrin
3) Coughing up the caseous material (self-debridement)

Question 19

Primary “virgin” TB usually occurs in:

Answer 19

base of lungs

Question 20

Secondary TB usually occurs in:

Answer 20

apex of lungs

Question 21

Reactivation TB usually occurs in:

Answer 21

immunocompromised patients

Question 22

M. avium (MAC) is present in environment and animals. It mostly occurs in what people?

Answer 22

Immunosuppressed patients

*exposure leads to respiratory or GI tract problems; not transmitted man-to-man

Question 23

How is the diagnoses of TB confirmed?

Answer 23

Chest X-ray

*need also acid-fast smear, culture, NA hybridization, PPD too