Antimycobacterial agents

Question 1

what is the shape of mycobacteria?

Answer 1

rod

Question 2

what is incorporated into the cell wall of mycobacteria?

Answer 2

mycolic acids

Question 3

what is the gram stain of mycobacteria?

Answer 3

poor gram stain, or not at all

Question 4

what is the stain used for mycobacteria?

Answer 4

acid fast

Question 5

which bacterial organism is stained using an acid fast stain?

Answer 5

mycobacterium

Question 6

where do mycobacteria replicate?

Answer 6

macrophages

Question 7

what is the route of transmission for m. tuberculosis?

Answer 7

respiratory droplets

Question 8

what type of organism is present in patients with latent TB infection?

Answer 8

inactive, contained tubercle bacilli

Question 9

what type of organism is present in patients with TB disease?

Answer 9

actie, multiplying tubercle bacilli

Question 10

what organisms are included in m. avium complex (MAC)?

Answer 10

m. avium

m. intracellulare

Question 11

what can MAC cause?

Answer 11

pulmonary disease in immuno-competent individuals, and disseminated disease in AIDS patients

Question 12

what is the route of transmission for MAC?

Answer 12

ingestion of contaminated food and water

respiratory droplets

Question 13

what is the most active drug used in the treatment of TB (active and latent)?

Answer 13

isoniazid

Question 14

isoniazid shares structural similarity with what vitamin?

Answer 14

B6 (pyridoxine)

Question 15

what is the MOA of isoniazid?

Answer 15

inhibits synthesis of mycolic acid - covalently binds with at least two proteins involved in mycolic acid synthesis

Question 16

what are the two mechanisms of resistance in isoniazid therapy?

Answer 16

mutation in Kat G gene - lack of prodrug activation

overexpression of Inh A protein - cannot inhibit mycolic acid synthesis

Question 17

what is essential in active TB treatment?

Answer 17

at least two antiTB agents always be used

Question 18

how is isoniazid absorbed?

Answer 18

GI tract

Question 19

what are the adverse effects of isoniazid?

Answer 19

hepatitis

peripheral neuropathy

Question 20

what is the first line treatment for active TB?

Answer 20

rifampin

Question 21

rifampin is also effective against what other organisms?

Answer 21

gram positive
gram negative
chlamydia

Question 22

what is the MOA of rifampin?

Answer 22

inhibits RNA synthesis
binds to bacterial DNA dependent RNA pol
penetrates most tissues, and phagocytic cells

Question 23

what is the mechanism of resistance for rifampin?

Answer 23

point mutations in bacterial RNA pol gene

Question 24

how is rifampin absorbed?

Answer 24

GI tract

Question 25

what are the adverse reactions to rifampin?

Answer 25

GI nervous system - headache, dizziness, fatigue hepatitis harmless, red-orange urine, feces, sweat, tears, saliva

Question 26

what are the important drug interactions of rifampin?

Answer 26

strong inducer of cyp450s - increases elimination of many drugs and drug classes

Question 27

in HIV patients rifampin should be replaced by what drug? why?

Answer 27

rifabutin less potent inducer of cyp450 enzymes

Question 28

rifabutin should replace rifampin in treatment of TB for what population?

Answer 28

HIV

Question 29

what is pyrazinamide?

Answer 29

used in multidrug regimen in treating active TB

Question 30

what is the proposed MOA of pyrazinamide?

Answer 30

inhibition of mycolic acid synthesis

Question 31

what is the mechanism of resistance for pyrazinamide?

Answer 31

mutation in pyrazinamidase enzyme

Question 32

what are the adverse reactions to pyrazinamide?

Answer 32

hepatotoxicity hyperuricemia

Question 33

what drug is used in combination therapy for active TB and m. avium infection?

Answer 33

ethambutol

Question 34

what is the MOA of ethambutol?

Answer 34

inhibits arabinosyl transferases (mycobacterial cell wall synthesis)

Question 35

what is the MOR of ethambutol?

Answer 35

point mutations in genes encoding arabinosyl transferase

Question 36

what are the adverse reactions of ethambutol?

Answer 36

retrobulbar neuritis | hyperuricemia

Question 37

what is the indication for streptomycin in TB therapy?

Answer 37

TB caused by strains resistant to other first line drugs

Question 38

what is the MOA of streptomycin?

Answer 38

interferes with bacterial protein synthesis

Question 39

streptomycin is effective against which TB organisms?

Answer 39

m. tubuerculosis | MAC species

Question 40

what is the MOR of streptomycin?

Answer 40

point mutations in ribosomal proteins

Question 41

what are the adverse reactions of streptomycin?

Answer 41

ototoxic | nephrotoxic

Question 42

what is the MOA of rifabutin?

Answer 42

inhibition of RNA polymerases

Question 43

rifabutin is more effective against what organisms?

Answer 43

MAC organisms

Question 44

what is the combination therapy for MAC organisms?

Answer 44

macrolide (clarithromycin, azithromycin) rifampin (or rifamycin) ethambutol streptomycin

Question 45

what is the combination therapy for MAC disseminated disease?

Answer 45

macrolide (clarithromycin, azithromycin) rifampin (or rifamycin) ethambutol

Question 46

what is the treatment for prophylaxis in HIV patients?

Answer 46

clarithromycin or azithromycin

Question 47

what is the treatment for leprosy?

Answer 47

dapsone clofazimine rifampin

Question 48

dapsone is a structural analog of what compound?

Answer 48

PABA

Question 49

what is the MOA of dapsone?

Answer 49

competitive inhibitor of folate synthesis