Anti-Mycobacterial Drugs (Tuberculosis/Leprosy/MAC) Flashcards Preview

Class: Immuno Block > Anti-Mycobacterial Drugs (Tuberculosis/Leprosy/MAC) > Flashcards

Flashcards in Anti-Mycobacterial Drugs (Tuberculosis/Leprosy/MAC) Deck (19)
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1

What is the cause of Mtb-mediated tissue injury and death?

HOST immune response of inflammation [CASEOUS NECROSIS]
NOT the specific toxin
Inflammation and host self-death in attempt to control intracellular bacterial growth

2

Most commonly recovered NON-TB, nonpathogenic Mycobacterium species __
Where is it found?

M. gordonae
Soil/Water

3

Greatest diagnostic test to diagnose Mtb

NAAT - Greater sensitivity and greater specificity than the conventional smear or culture

4

Difference between LTBI (latent tb infection) therapy versus active TB disease

LTBI - can use single or multi drug therapy
Active TB - ALWAYS use multi drug

5

Which first line drug targets arabinogalactan of the MYCOBACTERIAL cell wall AND is particularly effective against fast-growing EXTRACELLULAR Mtb?

Ethambutol (EMB)

6

3 Drugs that target mycolic acid of MYOBACTERIAL cell wall

FIRST-LINE: INH (isoniazid)
SECOND-LINE: PAS (p-aminosalicylic acid) + ETA (ethionamide)

7

Which first line drug inhibits the large subunit of RNA polymerase and inhibits RNA synthesis (release of nascent RNA) [particularly effective against slow-growing INTRACELLULAR Mtb]?

Rifampin

8

Which first line drug inhibits protein synthesis in DORMANT bacteria

Pyrazinamide

9

Which two first line anti-mycobacterial drugs are used for prophylactic treatment?

Rifampin
Isonozaid

10

Which two first line and one second-line drug are anti-mycobacterial pro-drugs? (Necessitate activation by bacteria for the drug to be effective)

Isoniazid
Pyrazinamide

PAS

11

Active form of INH (isoniazid)?
What bacterial enzyme mediates this conversion?
What does it target?

INH-NAD
Conversion by bacterial KatG (catalase-peroxidase)
Targets the Fab1 (InhA) of FASII - enzyme that elongates mycolic acid of the cell wall

12

Main side effect of INH _
Why? _
Management of this side effect _

Peripheral neuropathy
Due to pyridoxal deficiency (INH looks structurally similar to VitB6)
Management by VitB6 supplementation

13

Non-toxic side effect of rifampin on excreted body fluids (urine, sweat, tears)

Harmless purple/red in these fluids

14

Toxic side effects of rifampin

1) Flu-like symptoms
2) Induces CYP3A -> Increases elimination of other drugs
3) Can penetrate into CSF is patient also has meningitis

15

Advantages of rifabutin + Rifapentine over rifampin (RIF)

1) Higher potency
2) Longer half life
3) Greater membrane permeability - can infiltrate macrophages more easily
4) Less CYP3A induction -> Less excretion of other drugs (better if the patient is taking other medications such as anti-arrhythmic agents/HIV)

16

Active form of pyrazinamide __
What does the active form bind?

POA - pyrazinoic acid
Binds RpsA [ribosomal protein S1]
which inhibits S1 from binding tmRNA -> Prevents trans-translation mechanism -> Prevents rescue of stalled ribosomes -> Accumulation of misfolded peptides that do not get sent for degradation ->
DORMANT bacteria can not survive under these stressful conditions

17

Which anti-mycobacterial first-line drug should you NOT administer to children younger than 5yrs old? Why?

Ethambutol
Optic neuritis + Red-green color blindness

18

Treatment of MAC infection

MACROLIDES: Azithromycin + Clarithromycin
May also use ciprofloxacin, ethambutol and rifabutin

19

Who is most at risk for Mtb progression (reactivation/reinfection)? Why?

HIV - immunocompromised patients who do not have CD4+ Th cells to mediate cell-mediated immunity in the Langerhan giant cells - Can not contain bacteria because they can not form the granuloma around the bacteria (tubercle bacilli)