Lecture 8 - Mycobacterium Flashcards
According to the WHO, about 1/3 of the world’s population are infected with _______.
Tuberculosis
Symptoms of TB include:
- Lingering cough (with sputum and occasionally _____.
- Fever and ____ sweats.
- Constant _____
- Loss of appetite/nausea
- Severe ____ loss (consumption.)
- Progressive _____ destruction and death if untreated
- Can become _____.
- Blood
- Night
- Fatigue
- Weight loss (consumption)
- Progressive lung destruction
- Systemic
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.
Cell wall
Lipids
Mycolic acid
Lipids
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.
Acid-fast staining
_____ is the protein that is injected under the skin in a PPD test.
Tuberculin
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.)
Aerobe
37 degrees C
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.
22 hours
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 ______.
Drying
Latent
Infectious
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 ______.
Aerosols
Macrophages
Macrophages
Tubercle
Lymphocytes
Macrophages
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.
Calcified
Caseous
Latent TB can become reactivated if the patient becomes ______compromised, or if the lesion liquefies.
Immunocompromised
_____ T-cells are required to activate macrophages to keep M. Tuberculosis from growing.
CD4 t-cells
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.
CD4 T-cells
CD8 T-cells
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.
Inflammatory
Respire
Blood (sign of late TB)
MDR TB is resistant to isoniazid and ______. XDR TB is resistant to those and Fluoroquinilone and one more second-line drug.
Rifampin
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.
Mycolic Acid
Pro-drugs
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.
PPD
Blood
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.
Antibiotic
Tubercles
Prophylactic administration of INH and Rifampin are indicated for people with _____ disease or high risk for exposure.
Latent
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.
Avirulent
Bovis
Miliary
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 _____.
Hansen’s disease
33 degrees C
12-14 days
Mice
Another difference between M. Leprae and M. Tb is that M. Leprae is far _____ contagious. In fact, most people are immune.
LESS
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.
Peripheral nerves
Upper
Macrophages
Peripheral
Tuberculoid
Leprotamous
The treatment for M. Leprae takes about 6 months - 2 years (same as M. Tb) and is very effective prior to ____ damage.
Nerve
