Antimicrobial Agents -Antimycobacterial

Question 1

Out of the mycobacterium, which one is the opportunistic human pathogens?

Answer 1

M. avium-intracellulare complex

Question 2

What are mycobacterium defined by?

Answer 2

Their unique cell wall–Acid fast

[dense, high lipid, hydrophobic, difficult to penetrate, resistant to dehydration, acids and alkalis]

Question 3

When do we see meningitis with tuberculosis?

Answer 3

children under 5 in endemic areas

Question 4

Is mycobacterium tuberculosis an obligate human pathogen?

Answer 4

Yes

Question 5

Why is it important to distinguish latent TB from active disease?

Answer 5

Treatment for latent TB is different from active disease

[BUT THEY ARE NEITHER SYMPTOMATIC NOR INFECTIOUS]

Question 6

What is the purpose of whole blood assays for tuberculosis?

Answer 6

1. measure the patient’s gamma interferon response to M. tuberculosis specific antigens
2. Reduces/removes influence of BCG vaccination–QuantiFERON-TB Gold, T-SPOT.TB

Question 7

What are the 4 first-line drugs that are considered Anti-TB standard treatment?

Answer 7

1. isoniazid
2. rifampin
3. pyrazinamide
4. ethambutol
   [take 4 drugs for 2 months, 2 for 4 to 7 months]

Question 8

Why isn’t streptomycin a 1st line drug for TB?

Answer 8

increased resistance

Question 9

Why must we use combination therapy to treat active TB?

Answer 9

Drug resistant mutants occur-patients can harbor drug resistant bacteria and then long treatments make them the dominant strain- use more than one drug to avoid this
[10 up 8 is the magic number]

Question 10

Can latent TB be treated with a single drug?

Answer 10

yes

Question 11

What TB drugs inhibits cell wall synthesis 2? Disrupts: membrane, energy metabolism? Inhibits mRNA synthesis the prokaryotic beta subunit RNA polymerase?

Answer 11

1. Isoniazid, ethambutol
2. Pyrazinamide
3. Rifampin

Question 12

Can isoniazid be used as a single drug for treatment of latent TB? What is it activated by?

Answer 12

1. Yes

2. It is a prodrug activated by mycobacterial enzyme

Question 13

resistance to INH occurs in what 2 cases?

Answer 13

1. inhA over-expression

2. deletion of KatG

Question 14

In the case of INH causing peripheral neuropathy, what do you give the patient?

Answer 14

B6

Question 15

Is rifampin active against rapidly growing or slowly metabolizing bacilli? cidal or static?

Answer 15

Both–bactericidal

Question 16

How does resistance occur to rifampin?

Answer 16

mutation in rpoB gene

Question 17

Is Rifampin a p450 inhibitor?

Answer 17

No- P450 inducer [accelerates metabolism]

Question 18

Is ethambutol active against multiplying bacilli? static or cidal?

Answer 18

1. yes

2. bacteriostatic

Question 19

Ethambutol interferes in the biosynthesis of cell wall arabinogalactan…how is resistance to ethambutol conferred?

Answer 19

Mutations in embB which encodes arabinosyl transferases

Question 20

T-F—pyrazinamide is a prodrug metabolized via pyrazinamidase (pncA) to pyrazinoic acid

Answer 20

True

Question 21

MDR TB is resistant to what 2 drugs? What is extensively drug resistant XDR TB?

Answer 21

1. Isoniazid and rifampin2. MDR+resistance to fluoroquinolone and 1 of 3 injectables

Question 22

What are the 3 injectable TB drugswe should know?

Answer 22

amikacin, kanamycin, capreomycin

Question 23

A low pH renders what drug inactive?

Answer 23

streptomycin

Question 24

Resistance that is incurred because drugs are exported before it reaches target effects what 3 TB drugs?

Answer 24

1. Streptomycin
2. Isoniazid
3. Ethambutol

Question 25

What drugs are exceptions to being ineffective when TB is in a dormant non-replicating state?

Answer 25

Rifamycin and fluoroquinone

Question 26

Alteration of the enzyme that prevents the prodrugfrom becoming active affects which drugs?

Answer 26

pyraziinamide and isoniazid

Question 27

What are 3 characteristics of how M. Leprae is transmitted?

Answer 27

1. droplets through close freq contact.
2. host genetic factors effects
3. no impacted by aids

Question 28

Pauci-bacillary leprosy drug regimen?

Multi-bacillary leprosy drug regimen?

Answer 28

1. rifampicin and dapsone 6 months

2. rifampicin, dapsone, clofazimine for 12 mo.

Question 29

What is the regimen for antibiotics for buruli ulcers?

Answer 29

8 weeks rifampicin and streptomycin/amikacin

+surgery

Question 30

T-f–for the nontuberculous mycobacteria, detection means you have the disease?

Answer 30

False- it is ubiquitous, no person to person spread, opportunistic infections mainly in immunocompromised individuals

Question 31

M. kansasii, M. simiae and M. marinum are in what group?

Answer 31

Runyon 1 photochromogens

Question 32

M. scrofulaceum and M. szulgai are in what group?

Answer 32

Runyon 2 scotochromogens

Question 33

M. avium complex (MAC), M. ulcerans, M. xenopi,

M. malmoense, M. terrae, M. haemophilum and M. genavense are in what group?

Answer 33

Runyon 3- nonphotochromogens

Question 34

– M. abscessus
– M. chelonae
– M. fortuitum are in what group?

Answer 34

Runyon 4 rapid growers.

Question 35

What 2 drugs do we use for M. marinum?

Answer 35

Rifampin and ethambutol

Question 36

What is the suggested drug regimen for MAC?

Answer 36

1. clarithromycin or azithromycin
2. Rifatubin or rifampin
3. ethambutol

MWF 12 mo free of sputum or lifetime treatment

Question 37

Are drugs used for MTB complex good enough for NTM?

Answer 37

sometimes, but a lot of times resistance has formed

Question 38

key concepts for NTM-

Answer 38

– Determine species to select the best treatment
– Multi-drug therapy
– Colonization versus pathogen