Lecture 8 - Mycobacterium

Question 1

According to the WHO, about 1/3 of the world’s population are infected with _______.

Answer 1

Tuberculosis

Question 2

Symptoms of TB include:

1. Lingering cough (with sputum and occasionally _____.
2. Fever and ____ sweats.
3. Constant _____
4. Loss of appetite/nausea
5. Severe ____ loss (consumption.)
6. Progressive _____ destruction and death if untreated
7. Can become _____.

Answer 2

1. Blood
2. Night
3. Fatigue
5. Weight loss (consumption)
6. Progressive lung destruction
7. Systemic

Question 3

M. Tuberculosis is a slender rod (bacillus) with a seeming combination of gram negative and positive characteristics. It has a thick _______ ______ comprised of petidoglycan, but is mixed with _____ (i.e. ____ acid.) These ____ act as an outer membrane, similar to that of gram neg bacteria.

Answer 3

Cell wall

Lipids

Mycolic acid

Lipids

Question 4

Because of the lipid mixture that acts as an outer membrane, M. Tuberculosis must be stained with ____-fast staining. This reveals a reddish clumping of bacili.

Answer 4

Acid-fast staining

Question 5

_____ is the protein that is injected under the skin in a PPD test.

Answer 5

Tuberculin

Question 6

M. Tuberculosis is a strict ______ (makes sense given its location of initial infection - the lungs) and grows at _____ degrees C (not room temp.) In contrast, M. Leprae does not grow at this temp; it prefers something around 34 C (again, this should make sense given their respective areas of infection - Leprae on the skin/ extremities.)

Answer 6

Aerobe

37 degrees C

Question 7

The generation time for M. Tuberculosis is about _____ hours (which is relatively slow when compared to something like E. Coli which has a doubling time of about 20mins.) This relatively long doubling time lends itself to the 2-5 years it takes for the disease to cause death if untreated.

Answer 7

22 hours

Question 8

M. Tuberculosis is resistant to ______ and disinfectants, but is not resistant to heat. Keep in mind that its faux-outer membrane confers this resistance. Also keep in mind ______TB can not be transmitted. It must be ______.

Answer 8

Drying

Latent

Infectious

Question 9

M. Tuberculosis transmission and infection:

Exposure (inhalation of bacteria via _____) –> Bacteria reach lungs and enter alveolar ______ –> bacteria reproduce inside ______ because they prevent phagosome binding to lysosome –> lesions begin to form a _____ when ______ appear and activate infected ______.

Answer 9

Aerosols

Macrophages

Macrophages

Tubercle

Lymphocytes

Macrophages

Question 10

Tubercles can become ______ over time, showing up as a dark spot on an x-ray. Initially, they’re walled-off macrophages that have inhibited the growth of the bacteria. These macrophages begin to form ______ necrosis.

Answer 10

Calcified

Caseous

Question 11

Latent TB can become reactivated if the patient becomes ______compromised, or if the lesion liquefies.

Answer 11

Immunocompromised

Question 12

_____ T-cells are required to activate macrophages to keep M. Tuberculosis from growing.

Answer 12

CD4 t-cells

Question 13

HIV is a proponent for TB infection because the virus initially infects ____ T-cells, which are required to active macrophages and _____ T-cells in order to control TB infection.

Answer 13

CD4 T-cells

CD8 T-cells

Question 14

TB is fatal because uncontrolled growth causes destruction of lung tissue, largely by way of host ______ response (especially TNF-alpha.) This damage causes inability to ______ and/or _____ filling alveolar spaces. Less commonly, death can result from spread/systemic infection.

Answer 14

Inflammatory

Respire

Blood (sign of late TB)

Question 15

MDR TB is resistant to isoniazid and ______. XDR TB is resistant to those and Fluoroquinilone and one more second-line drug.

Answer 15

Rifampin

Question 16

Isoniazid (INH) and Pyrazinamide (PZA) both inhibit _____ _____ synthesis, which is a key component of the lipid mixture that acts as a faux outer-membrane in M. Tuberculosis. Both INH and PZA are administered as ____-drugs, which require enzymatic activation. Mutations in these enzymes would confer M. Tuberculosis with resistance to these antibiotics.

Answer 16

Mycolic Acid

Pro-drugs

Question 17

For people who have received the BCG vaccine, a ____ test would not be the best method to determine if they’ve been infected or come in contact with TB. Instead, a ____ test should be used.

Answer 17

PPD

Blood

Question 18

A sputum test for TB allows for culturing of the bacteria to determine ______ sensitivity and species, but unfortunately this takes around 2-8 weeks. A chest x-ray might reveal calcified _____ in the lungs.

Answer 18

Antibiotic

Tubercles

Question 19

Prophylactic administration of INH and Rifampin are indicated for people with _____ disease or high risk for exposure.

Answer 19

Latent

Question 20

The BCG vaccine is a live, _____ strain of Mycobacterium ____. The vaccine is more effective against meningial and ______ TB in young children than it is against pulmonary. In countries with low incidence of TB, this vaccine is rarely used because it interferes with the ability to use the PPD test.

Answer 20

Avirulent

Bovis

Miliary

Question 21

M. Leprae is the causative agent for ____ disease (Leprosy.) It’s optimum growth temp is _____ degrees C (lower than M. TB.) It has a VERY SLOW doubling time of about ___-___ days. It’s also hard to culture, as it’s only known to grow in armadillos and on the footpads of _____.

Answer 21

Hansen’s disease

33 degrees C

12-14 days

Mice

Question 22

Another difference between M. Leprae and M. Tb is that M. Leprae is far _____ contagious. In fact, most people are immune.

Answer 22

LESS

Question 23

Hansen’s disease affects the skin, ___ nerves, and _____ respiratory tract. M. Leprae infects _______ (like M. Tuberculosis) and Schwann cells (resulting in thickening of _____ nerves and local anesthesia.) Cell-mediated immunity is active in _____ but not _______ Leprosy.

Answer 23

Peripheral nerves

Upper

Macrophages

Peripheral

Tuberculoid

Leprotamous

Question 24

The treatment for M. Leprae takes about 6 months - 2 years (same as M. Tb) and is very effective prior to ____ damage.

Answer 24

Nerve