Antibiotics V: Antimycobacterial Agents

Question 1

definition of multi-drug resistant TB

Answer 1

resistant to isoniazid and rifampin

Question 2

definition of extensively drug resistant TB

Answer 2

resistant to isoniazid, rifampin, fluoroquinolones, and aminoglycosides

Question 3

MOA: inhibits synthesis of mycolic acid

Answer 3

isoniazid

Question 4

bactericidal to active bacilli; bacteriostatic to quiescent bacilli

Answer 4

isoniazid

Question 5

prodrug activated by mycobacterial catalase/peroxidase (KatG) to a free radical that covatently binds to NAD+ and NADP+ to inhibit mycolic acid synthesis

Answer 5

isoniazid

Question 6

Half-life is 1 hr in rapid acetylators, 3 hr in slow acetylators

Answer 6

isoniazid

Question 7

used alone for latent TB and in combination for active TB

Answer 7

isoniazid

Question 8

Adverse reactions: peripheral neuropathy due to deficiency in pyridoxine; hepatotoxicity

Answer 8

isoniazid

Question 9

inhibits DNA-dependent RNA polymerase

Answer 9

rifampin

Question 10

used in combination for treatment of TB; leprosy; broad spectrum antibiotic

Answer 10

rifampin

Question 11

Adverse reactions: hepatotoxicity, discoloration of body fluids, strong induction of many CYP isoforms

Answer 11

rifampin

Question 12

disrupts assembly of mycobacterial cell wall (mycobacterial arabinosyl transferase III)

Answer 12

ethambutol

Question 13

Therapeutic uses: combo treatment of TB

Answer 13

ethambutol

Question 14

Adverse reaction: optic neuritis

Answer 14

ethambutol

Question 15

Prodrug converted to pyrazinoic acid by mycobacterial pyrazinamidase

Answer 15

pyrazinamide

Question 16

used as “sterilizing” agent against residual organisms that may cause relapse

Answer 16

pyrazinamide

Question 17

Adverse effects: hepatotoxicity, hyperuricemia

Answer 17

pyrazinamide

Question 18

for severe life-threatening forms of TB; active against extracellular bacilli

Answer 18

streptomycin