Infectious Diseases II: Tuberculosis

Question 1

What pathogen causes TB?

Answer 1

Mycobacterium tuberculosis

Question 2

What type of bacteria is mycobacterium tuberculosis?

Answer 2

Aerobic, non-spore forming bacillus

Question 3

TB is transmitted via….

Answer 3

aerolized droplets and is highly contagious

Question 4

2 phases of TB:

Answer 4

latent phase (no symptoms)
active phase (symptoms and highly contagious)

Question 5

Diagnosis of latent TB

Answer 5

Tuberculin skin test

False + can occur in pts that recieved bacille Calmette-Guerin (BCG) vaccine - used in countries with high incidence of TB

Question 6

Does latent TB require treatment?

Answer 6

It is strongly recommended because it greatly reduces the incidence of active disease

Question 7

Treatment options for latent TB: [3]

Answer 7

1. Isoniazid (INH) 300 mg daily or 15 mg/kg 2x/week x 9 MONTHS (preferred for HIV pts, pregnant women, children)
2. Rifampin 600 mg daily x 4 MONTHS
3. INH and Rifapentine (Priftin) once weekly for 12 weeks (not used in HIV pts, pregnant women and kids under 2)

Question 8

How to diagnose active TB

Answer 8

skin test + sputum culture (acid fast bacilli)

PCR testing

Question 9

Usual active TB treatment

Answer 9

Intensive phase x 2 months (consist of 4 drugs)

Continuation phase x 4 months (7 months in some cases) - consist of 2 drugs, usually isoniazid + rifampin

Question 10

Definition of multi-drug resistant TB

Answer 10

Tb that is resistant to BOTH isoniazid and rifampin

Requires treatment for up to 24 months
Use 2nd line agents such as quinolones, IV streptomycin, amikacin, etc.

Question 11

How long does it take to get cultures and susceptibilities for TB?

Answer 11

up to 6 weeks

Question 12

Drugs used for intensive phase

Answer 12

RIPE used for 2 months
Rifampin (RIF)
Isoniazid (INH)
Pyrazinamide (PZA)
Ethambutol

Ethambutol can be stopped if bacteria is susceptible to other drugs

Question 13

Rifampin clinical info

Answer 13

Rifadin
CI with use of protease inhibitors
Incr. LFTs, turn body secretions orange-red, flu-like symptoms, GI upset, rash, itching

Potent inducer of many CYP enzymes including 3A4

Question 14

Rifampin dose

Answer 14

10 mg/kg daily (max 600 mg)

can be given 2-3x/week

Question 15

What drug can be used in place of rifampin for pts with HIV that are taking protease inhibitors?

Answer 15

Rifabutin 300 mg daily

Question 16

Isoniazid clinical info

Answer 16

cannot be used in pts with hepatitis/acute liver disease
Dose: 5 mg/kg (max 300 mg) daily or 15 mg/kg (900 mg) 2-3x/week
Side effects: HA, GI upset, incr LFTs, drug-induced lupus, +Coombs test, peripheral neuropathy

Question 17

What help decrease the risk of INH-assoc. peripheral neuropathy?>

Answer 17

Pyridoxine 25 mg daily

Question 18

Brand name of Rifampin + isoniazid:

Answer 18

Rifamate

Question 19

Brand name of rifampin + isoniazid + pyrazinamide

Answer 19

Rifater

Question 20

Pyrazinamide dose

Answer 20

weight based dose:
20-25 mg/kg/day
40-55 kg: 1 g/day
76-90 kg: 2 g/day (max dose)

CrCL < 30: extend interval

Question 21

Pyrazinamide side effects

Answer 21

do not use during acute gout attack, severe liver damage

Incr LFTs, incr uric acid, GI upset, myalgias, malaise

Question 22

Rifampin should be taken with a meal (t/f)

Answer 22

False take on empty stomach

Question 23

Ethambutol dose

Answer 23

15-20 mg/kg (max 1.6 g)
can be given 2-3x/week as well

CrCL< 50: extend interval

Question 24

Ethambutol side effects

Answer 24

Optic neuritis, other visual disturbances
incr LFTs
rash
HA

Question 25

Significant drug interactions with rifampin

Answer 25

CYP inducer decr conc of many drugs:
protease inhibitors
warfarin
other anticoagulants
oral contraceptives

Question 26

Isoniazid interactions

Answer 26

weak/mod inhibitor of 1A2, 2C19, 2C9, 2D6, 3A4