Clinical 2 - Antibiotics > 10 - Tuberculosis > Flashcards

10 - Tuberculosis Flashcards

(62 cards)

Study These Flashcards
1
Q

What 2 types of populations have a higher incidence of Tb in Canada?

A
  • Canadian-born Aboriginal

- Foreign born

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What province/territory has highest incidence of Tb ?

A

North (the territories)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What bug causes Tb?

A

Mycobacterium tuberculosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe Mycobacterium tuberculosis

A
  • bacillus
  • aerobic and anaerobic, intracellular and extracellular
  • slow growing, latent, dormant states
  • multi-drug resistance

**using 1 drug to treat Tb is not effective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the transmission of Tb

A
  • communicable disease, aerosolized droplets
  • enters bronchioles and alveoli, settles in lower lobes
  • first-line macrophage-mediated immunity
  • followed by T-cell immunity over 2-8 weeks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the risk factors for Tb?

A
  • close contacts especially laryngeal or pulmonary TB (positive smear/culture stages)
  • endemic areas (Northern Canada)
  • poor or crowded living conditions, homelessness, correctional facilities
  • healthcare workers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Of those who get the initial infection, how many develop the disease and how many have a latent Tb infection?

A

5% have primary disease

95% have latent TB infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Of those who have the latent TB infection, how many will have a reactivation and how many will have no disease?

A

5% will have a reactivation of Tb

90% will have no disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe a latent TB infection?

A
  • asymptomatic or mildly symptomatic, non-contagious
  • normal X-ray, negative sputum stain and culture results
  • lymphatic spread to regional nodes, lung apices .. less commonly bone marrow, liver, spleen, kidney, meninges
  • latent or dormant in seeded foci (Ghon nodes) for months to years
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How do we diagnose a latent Tb infection?

A

1) TST (Tuberculin skin test)
- heat sterilized, purified protein derivative
- delayed T-cell hypersensitivity response, induration within 48-72 hours
- false negative results if cutaneous anergy (pre-conversion, neonate, elderly, HIV, lymphoma, chemotherapy, corticosteroids); use positive control mumps or Candida
- does not distinguish latent from active disease !!!!, other mycobacterial infection or prior BCG vaccine

2) IGRA - interferon gamma release assay
- blood test measures T-cell release of IFN-gamma
- does not distinguish latent from active disease; more specific than TST in patients vaccinated with BCG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does a TST result > 10 mm mean?

A

TST conversion (within 2 years)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

In people who have been exposed to Tb in the past 2 years, they are at a higher risk of it becoming active. If you give them prophylaxis, you can reduce activation by ____%.

A

90%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the treatment for latent TB infection?

A

INH daily x 9 months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is an alternative treatment for latent TB infection?

A

RMP daily x 4 months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

INH and RMP are both associated with ______

A

hepatotoxicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Primary TB:

Early progression typically within ____ months of exposure

A

4-12

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Primary TB:

Risk factors?

A
  • age

- immune function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Primary TB:

Most common in ?

A

lymph node or pleural disease

in lungs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Primary TB:

Disseminated including CNS more common in ?

A

infants, immunocompromised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Reactivation TB:

Late progression ____ months or longer after exposure

A

18-24

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Reactivation TB:

Most common upper lobe pulmonary disease (_____)

A

pneumonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Reactivation TB:

Extra-pulmonary more common in _______

A

immunocompromised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are some high risk factors for active TB infection ?

A
  • AIDS/HIV
  • Transplant
  • Lung disease (silicosis)
  • Hemodialysis
  • Carcinoma in head and neck
  • Recent TB infection in the past 2 years
  • Abnormal chest x ray
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Clinical signs and symptoms of active Tb ?

A
  • dry then productive cough > 2 weeks
  • hemoptysis (coughing up blood), chest pain
  • fever, night sweats
  • anorexia, weight loss (advanced disease)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What type of microbiological testing occurs for active Tb?
- acid-fast bacilli (AFB) smear stain is rapid and inexpensive, positive results in over 50% of cases (modest sensitivity) - mycobacterial culture/susceptibility testing is gold standard (2-8 weeks for complete results) - molecular diagnostics (PCR) and susceptibility screening
26
A radiograph is not ______
conclusive
27
Treatment of active TB infection: | ___% mortality without treatment
>50%
28
Goals of treating an active TB infection ?
- rapidly kill and eliminate MTB to cure clinical disease (without relapse), prevent complications and reduce mortality - prevent antimicrobial resistance - prevent transmission
29
What are the principles of anti-TB drugs?
- Combination therapy optimizes MTB killing & prevents resistance - Adherence optimizes efficacy and minimizes resistance - Drug dosing, PK-PD and role of TDM (therapeutic drug monitoring) not well understood - Follow-up sputum samples monthly until 2 consecutive negative culture results, predicts cure - Isolation to prevent transmission for initial 1-2 weeks and until 3 consecutive negative AFB smears
30
What is Regimen 1 for treating Tb?
Initial phase (first 2 months): - INH - isoniazid - RMP - rifampin - PZA - pyrazinamide - EMB - ethambutol daily or 5 days/week Continuation phase: - INH for 4 months - RMP for 4 months daily or 3 times/week
31
What is Regimen 2 for treating Tb ?
Initial phase (first 2 months): - INH - isoniazid - RMP - rifampin - EMB - ethambutol daily or 5 days/week Continuation phase: -INH for 7 months RMP for 7 months daily or 3 times/week
32
What is the Regimen for the elderly?
Initial phase (first 2 months): - INH - isoniazid - RMP - rifampin - EMB - ethambutol daily or 5 days/week Continuation phase: -INH for 7 months RMP for 7 months daily or 3 times/week
33
What is the Regimen if you're pregnant ?
``` Initial phase (first 2 months): -INH -RMP -EMB +/- PZA ``` daily or 5 days/week Continuation phase: - INH - RMP * for 7 months if PZA not used * for 4 months if PZA used daily or 3 times/week
34
Why is EMB (ethambutol added) ?
- incase there is restart bug to one or more of the first 3 meds - it is D/C at the time that you know it is sensitive to the other 3 meds
35
Dose of Isoniazid?
300 mg daily
36
Dose of Rifampin?
600 mg daily
37
Dose of Pyrazinamide?
20-25 mg/kg daily
38
Dose of Ethambutol?
15-20 mg/kg daily
39
Which meds need dosage adjustment with renal failure?
Pyrazinamide | Ethambutol
40
What dose of Pyrazinamide should be recommended for a CrCl < 30 or on hemodialysis ?
25-35 mg three times/week *normal dose = 20-25 mg/kg DAILY
41
What dose of Ethambutol should be recommended for a CrCl < 30 or on hemodialysis ?
15-25 mg three times/week *normal dose = 15-20 mg/kg DAILY
42
What are the 1st line agents?
- Isoniazid - Rifampin - Pyrazinamide - Ethambutol
43
Describe: | Isoniazid
- extra-cellular (doesn't go into cells) - bactericidal - inhibits protein, nucleic acid, lipid, mycelia synthesis in cell division
44
Describe: | Rifampin
- intra/extra-cellular - bactericidal - inhibits DNA-dependent RNA polymerase
45
Describe: | Pryazinamide
- intra-cellular - rapidly bactericidal - converted to pyrazinoic acid - toxicities of PZA limit it's long term use
46
Describe: | Ethambutol
- intra-cellular - bacteriostatic - inhibits metabolite & RNA synthesis
47
Why is EMB not the optimal anti-Tb drug?
bc it's static, not cidal | -only added on in case of resistance to the other 3 bugs
48
When are the 2nd line agents used?
if there is first-line drug resistance or intolerance
49
What are the 2nd line agents used for Tb?
- Fluoroquinolones (Levo/Moxi) | - Aminoglycosides (Amikacin/Streptomycin)
50
% of adverse effects for INH + RMP + PZA
18%
51
% of adverse effects for INH + RMP
7%
52
% of adverse effects for INH
6%
53
Side effects of INH
- Hepatotoxicity - LFTs, hepatitis, necrosis - Hypersensitivity - Peripheral neuropathy - Nausea, vomiting
54
What does hepatotoxicity increase with?
- increases with age, female, pre-existing liver disease, alcohol consumption, other hepatotoxins * Monitor baseline at 2 weeks and monthly
55
INH is an inhibitor of CYP 2C9 and 3A4 which means it interacts with what drugs?
- phenytoin - carbamazepine - warfarin
56
______ reduce absorption of INH
antacids
57
Side effects of Rifampin
- hepatotoxicity - hypersensitivity - nausea, gastritis - orange-red discolouration of saliva, urine, tears
58
What does Rifampin induce ?
CYP 2C9 and PgP
59
Side effects of PZA ?
- hepatotoxicity - hypersensitivity - hyperuricemia, arthralgias - nausea
60
Side effects of EMB?
- ocular neuritis (dose dependent) - hypersensitivity - CNS, peripheral neuritis *eye exams are indicated for ppl on EMB
61
How would you treat a drug-induced rash while on Tb meds?
- D/C TB drugs and start FQ + other second line agent (like Amikacin) - Review history for other possible causes - When rash resolves, restart one TB drug (ex. INH) - After 3 days, restart second TB drug (ex. RMP) - After 3 days, restart EMB *Once you know INH and RMP are fine, D/C FQ - After 3 days and if rash does not recur, assume PZA - If rash recurs with any of the above, discontinue agents dn start all remaining TB drugs - Adjust regimen based on agents discontinued
62
How would you treat a drug-induced hepatitis while on Tb meds?
- Discontinue TB drugs and start FQ + other second line drug - Review history for other possible causes, alcohol or other medications - Check viral hepatitis serologies - When transaminases return to normal, restart RMP - After 2 weeks, restart INH (unless initial severe toxicity ex. ALT > 1000) - After 2 weeks, if transaminases remain normal assume PZA - If hepatitis recurs with any of the above, D/C agent and start all remaining TB drugs - Adjust regimen based on agent's discontinued
Clinical 2 - Antibiotics
flashcards
Decks in class (14)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions