Mycobacterial Treatment

Question 1

Characteristics of Mycobacteria
Shape
Stain
Replication location
Growth pace
May form?
Cell walls are rich in?

Answer 1

Rod shaped
Acid fast stain...they don't gram stain
Replicate within macrophages
Generally slow growing
May form filaments
Lipid-rich cell walls

Question 2

Most infected individuals have what kind of infections?

Answer 2

Latent infections

Question 3

Transmission is primarily through

Answer 3

Respiratory droplets

Question 4

When may TB become disseminated?

Answer 4

In immunocompromised individuals

Question 5

Features of latent TB infections 
activation state
chest xray
sputum and cultures
symptom presentation
infectious state
case or not

Answer 5

Inactive and non-replicating
Chest xray normal
Sputum and cultures are negative
Asymptomatic
Not infectious
Not a case of TB

Question 6

Features of TB disease
activation state
chest xray
sputum and cultures
symptom presentation
infectious state
case or not

Answer 6

Active and replicating
Abnormal chest xray
Sputum and cultures MAY be positive
Symptomatic 
Often infectious before treatment
A case of TB

Question 7

Obstacles to TB Treatment

Answer 7

organism grows slowly
organism remains viable but dormant
rapid development of resistance
toxicity with treatment–encourages non-compliance

Question 8

Solutions to obstacles

Answer 8

Regimens contain multiple drugs
Drugs taken regularly
Drug therapy continues for long time

Question 9

Rifamycin MOA

Answer 9

Inhibits RNA synthesis

Question 10

Streptomycin MOA

useful for

Answer 10

Inhibition of protein synthesis at 30S

Used for combination treatment of RESISTANT TB

Question 11

Isoniazid and ethionamide MOA

Answer 11

inhibit mycolic acid synthesis

Question 12

Ethambutol MOA

Answer 12

Inhibits cell wall synthesis

Question 13

Pyrazinamide MOA

Answer 13

Inhibits membrane synthesis

Question 14

M. avium complex (MAC) causes pulmonary disease and disseminated disease in which populations

Answer 14

Pulmonary disease in immunocompetent patients

Disseminated disease in immunocompromised patients, mainly AIDS patient population

Question 15

MAC primarily acquired through which route?

Answer 15

Ingestion of contaminated food and water

Question 16

Preferred Regimen (4 drugs)

Answer 16

Isoniazid
Rifamycin
Pyrazinamide
Ethambutol

Question 17

Continuation Regimen (2 drugs)

Answer 17

Isoniazid

Rifamycin

Question 18

Treatment Regimen for Latent TB (3 drugs)

Which one is drug of choice for latent TB?

Answer 18

Isoniazid* drug of choice
Rifapentine
Rifampin

Question 19

INH is bactericidal for?
Penetrates which cell type?
One reason it can cause peripheral neuropathy

Answer 19

Bactericidal for actively growing bacilli
Penetrates macrophages
Structurally similar to pyridoxine

Question 20

INH MOA
Delivered as a…?
What activates INH

Answer 20

Inhibits synthesis of mycolic acid (essential component of cell wall)
Delivered as a prodrug and is activated by mycobacterial catalase-peroxidase enzyme (Kat G)

Question 21

INH microbial activity

Answer 21

considered one of the safest and msot effective antimycobacterial agents available

Question 22

Two reason for resistance against INH

Answer 22

1. mutation in Kat G gene (no longer activated)

2. Overexpression of the InH A protein (involved in mycolic acid synthesis)

Question 23

What group of people are more prone to develop toxicity from INH?

Answer 23

Slow acetylators (inactivators)

Question 24

The risk of INH induced hepatitis increases with (blank) and is greater in individuals with (blank)

Answer 24

Increases with age and alcoholics

Question 25

Peripheral neuropathy most commonly seen in (5)

Answer 25

1. Slow metabolizers 2. Malnourished 3. Alcoholics 4. Diabetic 5. AIDS

Question 26

Rifampin MOA

Answer 26

Inhibits RNA synthesis by binding to bacterial DNA-dependent RNA polymerase Penetrates most tissues as well as phagocytic cells

Question 27

Most common side effect with Rifampin use in those with liver disease?

Answer 27

Hepatitis

Question 28

HIV patients and rifampin use

Answer 28

Rifabutin should be substituted for rifampin

Question 29

Pyrazinamide is used almost exclusively in...

Answer 29

combination therapy

Question 30

Pyrazinamide activated by

Answer 30

bacterial pyrazinamidase enzyme

Question 31

Pyrazinamide is highly effective against

Answer 31

intracellular mycobacteria

Question 32

Most common side effect associated with Pyrazinamide

Answer 32

Hyperuricemia/gout issues

Question 33

Ethambutol used almost exclusively for... | But also used for

Answer 33

Part of the 4 drug combinations used to treat active TB | Also used to treat MAC bacteria

Question 34

Ethambutol MOA

Answer 34

Inhibits arabinosyl transferases which are involved in mycobacterial cell wall synthesis

Question 35

Ethambutol resistance

Answer 35

Point mutations in genes coding for arabinosyl transferases

Question 36

Ethambutol adverse reactions (2)

Answer 36

1. Retrobulbar neuritis/color blindness | 2. Hyperuricemia (less frequent that pyrazinamide)

Question 37

Streptomycin current use

Answer 37

Treatment of TB caused by resistant strains

Question 38

Streptomycin MOA | Works well against...

Answer 38

Interferes with bacterial protein synthesis | Works on extracellular organisms

Question 39

Rifabutin use (2)

Answer 39

1. Greater activity against MAC organisms that rifampin | 2. Substituted for rifampin in the treatment of HIV patients who also have TB

Question 40

MAC treatment (3...maybe 4)

Answer 40

1. Macrolide 2. Rifampin (or other rifamycin) 3. Ethambutol 4. May use streptomycin

Question 41

Multidrug regimen of leprosy (3)

Answer 41

Dapsone Clofazimine Rifampin