41: antimycobacterial

Question 1

KatG gene mutation results in resistance to?

Answer 1

isoniazid

Question 2

mycolic acid synthesis inhibition is MoA of?

Answer 2

isoniazid

Question 3

1st line drugs for M TB? (4)

Answer 3

isoniazid
rifampin
pyrazinamide
ethambutol

Question 4

RoA of Isoniazid

Answer 4

oral or parenteral (IM)

Question 5

If isoniazid resistance is observed what can we use?

Answer 5

rifampin

Question 6

which 1st line mycobacterial drugs has bacteriostatic action?

Answer 6

ethambutol

Question 7

INH prophylaxis is given to?

Answer 7

in person with positive tuberculin skin test who meets the criteria:

1. HIV +
2. recently infected
3. X ray shows nonprogressive TB
4. illicit injected drug use
5. DM
6. immunosuppression

Question 8

which drug is activated by mycobacterial catalase-peroxidase

Answer 8

isoniazid

Question 9

isoniazid is active against which mycobacteria?

Answer 9

M tb

M kansasii

Question 10

which antimycobacterial drugs are metabolized by acetylation? (2)

Answer 10

isoniazid

dapsone

Question 11

vitamin B6 deficiency is observed as adverse effect of ? (2)

Answer 11

isoniazid

dapsone

Question 12

peripheral neuritis in isoniazid is more likely seen in which phenotype ?

Answer 12

slow acetylators

Question 13

to prevent peripheral neuritis we can supplement?

Answer 13

vitamin B6 - pyridoxine

Question 14

RoA of rifampin

Answer 14

oral , IV

Question 15

MoA of ethambutol

Answer 15

Inhibit arabinosyl transferase and synthesis of arabinogalactan for cell wall.

Question 16

resistance to ethambutol is gained by mutations in:

Answer 16

arabinosyl transferase.

Question 17

adverse effect of ethambutol?

Answer 17

Optic neuritis, Impaired red-green color discrimination.
Hyperuricemia; GOUT.
Hepatitis and thrombocytopenia.

Question 18

contraindication for ethambutol?

Answer 18

children too young to asses visual acuity

Question 19

ethambutol is active against which mycobacteria?

Answer 19

M tb

MAI

Question 20

treatment regimen for MAI?

Answer 20

Treatment: azithro/clarithromycin + ethambutol +/- rifabutin

Question 21

incase if resistance to rifampin we use?

Answer 21

rifabutin

Question 22

which antimycobacterial agent is more rapidly bactericidal than others, and has sterilizing effect?

Answer 22

pyrazinamide

Question 23

which agent is a nicotinamide derivative?

Answer 23

pyrazinamide

Question 24

2 known mechanisms of action of pyrazinamide

Answer 24

1. inhibition of fatty acid syntesis

2. inhibits ribosomal translation of mRNA

Question 25

inhibition of ribosomal mRNA , mechanism of pyrazinamide helps it to kill _____ TB?

Answer 25

dormant (nongrowing)

Question 26

RoA of pyrazinamide

Answer 26

oral

Question 27

mutation of which enzyme results in resistance to pyrazinamide?

Answer 27

pyrazinamidase

Question 28

adverse effects of pyrazinamide

Answer 28

``` Arthralgia. Hyperuricemia gout. Hematologic toxicity. Hepatitis increase in serum iron concentration. ```

Question 29

pyrazinamide is bactericidal or bacteriostatic?

Answer 29

bactericidal

Question 30

which first line mycobacterial is broad spectrum?

Answer 30

rifampin

Question 31

rifampin is active against which Mycobacteria?

Answer 31

M tb MAI M kansasii M leprae

Question 32

MoA of rifampin

Answer 32

: binds to B-subunit (of DNA dependent RNA polymerase) → inhibits DNA transcription and RNA synthesis

Question 33

clinical indications of rifampin? (

Answer 33

1. TB 2. leprosy 3. TB meningitis 4. prophylaxis (INH alternative, exposure to H influenza , prevent meningococcal disease) 5. eliminate staphylococcal carriage 6. treat staph infections: endocarditis 7. occasionally: legionella pneumophila

Question 34

which drug is used in treatment of lepromatous leprosy but not for tuberculoid leprosy?

Answer 34

clofazimine

Question 35

regimen for leprosy? (3)

Answer 35

dapsone + clofazimine + rifampin

Question 36

resistance to rifampin is gained by which mechanism?

Answer 36

decreased affinity of RNA polymerase to drug

Question 37

reddish orange to brown discoloration of saliva, tears, urine is adverse effect of?

Answer 37

rifampin | - also causes permenant staining of contact lenses

Question 38

which 1st line antimycobacterial agent causes hepatotoxicity and nephrotoxicity?

Answer 38

rifampin - hepatitis - cholestatic jaundice - acute intersitial nephritis - light-chain proteinuria

Question 39

rifampins drug interactions are:

Answer 39

Macrolides - Benzodiazepines - Calcium channel blocker Digoxin - Estrogens - Sulfonylureas - Theophylline Warfarin

Question 40

long acting rifamycin derivative is called?

Answer 40

rifapentine

Question 41

highly lipophillic derivative of rifamycin? (take with food to avoid irritation)

Answer 41

rifabutin

Question 42

if HIV patient is on protease inhibitor, which drug is preffered to use in MTB regiment?

Answer 42

rifabutin

Question 43

TB aminoglycosides are?

Answer 43

amikacin kanamycin streptomycin

Question 44

which aminoglycoside for M TB treatment is contraindicated in pregnant women?

Answer 44

streptomycin

Question 45

ROA of M tb aminoglycosides?

Answer 45

parenteral

Question 46

which aminoglycoside is more active than streptomycin?

Answer 46

amikacin

Question 47

MoA of Bedaquiline?

Answer 47

acts by blocking proton pump for ATP synthase in M tb

Question 48

bedaquiline is approved for treating?

Answer 48

MDR TB

Question 49

which antimycobacterial agent prolongs QT interval? and what should u consider doing before taking drug?

Answer 49

bedaquiline | perform ECG before taking drug

Question 50

sulfones MoA?

Answer 50

same as sulfonazmide: inhibit dehydropteorate synthase --> inhibits folic acid synthesis

Question 51

dapsone belongs to which class of drugs?

Answer 51

sulfones

Question 52

in patient with G6PDH deficiency which drug can cause an adverse effect?

Answer 52

dapsone, can cause hemolytic anemia

Question 53

adverse effects of dapsone ? (7)

Answer 53

1. gi disturbance 2. peripheral neuropathy 3. optic neuritis, blurred vision 4. proteinuria, nephrotic syndrome 5. lupus erythematous-like syndrome 6. hematologic toxicity 7. G6PDH def --> hemolytic anemia

Question 54

which antibiotic has antimycobacterial and antiinflammatory effects?

Answer 54

clofazimine

Question 55

clofazimine is bacteriostatic against which mycobacteria and bacteriocidal against which?

Answer 55

bacteriostatic --> M leprae bactericidal --> M tb remember: is also acitive against MAI

Question 56

half life of clodazimine?

Answer 56

70 days

Question 57

if i say phenazine dye, what comes to ur mind?

Answer 57

clofazimine

Question 58

photosensitivity and hepatitis, also discoloration of body secretions are adverse effects of?

Answer 58

clofazimine

Question 59

clinical indications of clofazmine?

Answer 59

1. lepromatous leprosy (used with dapsone and rifampin) | 2. erythema nodosum leprosum - due to its inflammatory effects

Question 60

which drug was banned due to phocomelia in offsprings of women who took drug during pregnancy?

Answer 60

thalidomide

Question 61

which drug has orphan status?

Answer 61

thalidomide

Question 62

which antimycobacterial drug is also used for legionella pneumophila ?

Answer 62

rifampin

Question 63

for treatment of prosthetic valve endocarditis we use rifampin in combination with?

Answer 63

gentamicin / vancomycin

Question 64

rifampin is used in prevention of meningococcal disease , but the preffered drugs for this are?

Answer 64

ceftriaxone / ciprofloxacin