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PM2C: Therapeutics and Patient Care: Summer > Respiratory: TB > Flashcards

Respiratory: TB Flashcards

1
Q

What is Tuberculosis (TB)?

A

Infectious disease caused by bacteria belonging to Mycobacterium tuberculosis complex

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2
Q

Why is TB different from gram positive and negative bacteria? What is it and how fast does it grow?

A
  1. Obligate Aerobes parasites

2. Slow growing: incubation period about 2 to 10 weeks

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3
Q

What is the transmission route for TB?

A

Respiratory route

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4
Q

What does TB cause?

A
  1. Lung lesions
  2. Pulmonary disease
  3. Extra pulmonary disease
    - Thoracic lymph nodes
    - CNS: meninges
    - Circulatory system
    - Bones, joints and skin
    - Intestine, peritoneum, eyes
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5
Q

Explain how in a clinical environment, TB is transmitted?

A
  1. Sneezing leads to exposure to tubercle bacilli
  2. Smallest droplets evaporate leading to bacilli that reach alveoli (MAIN ONE)
  3. Medium droplets: trapped and cleared in upper airways
  4. Largest droplets: fall to the ground and persist in dust
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6
Q

Which type of TB only makes it potentially infectious to others and how do you test for it?

A
  1. Pulmonary TB

2. Test: sputum smear positive

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7
Q

What does a TB infection lead to and what type of TB isn’t infectious?

A
  1. Leads to latent TB which can be reactivated later in a lifetime
  2. Latent TB isn’t infectious
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8
Q

What patients are in the risk groups that are more likely to catch TB?

A
  1. Close contacts of TB patient (sputum smeared positive diseased ones)
  2. People from countries with high prevalence of TB
  3. Casual contact if immunosuppresed (high dose steroids)
  4. HIV
  5. Chronic renal failure or in haemodialysis
  6. Injecting drug users and alcoholics
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9
Q

What are some symptoms of pulmonary TB?

A
  1. Productive Cough that lasts more than 3 weeks with purulent sputum
  2. Weight lost
  3. Malaise
  4. Fever
  5. Night sweats
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10
Q

How do you diagnose TB and respiratory active TB?

A
  1. Symptoms
  2. Sputum microscopy/culture
  3. Chest radiography

(top 3 respiratory active TB)

  1. Tuberculin skin testing
  2. Blood based immunological test
    - Interferon gamma test in cells
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11
Q

How does the sputum microscopy diagnosis work?

A
  1. Acid fast staining of sputum smears (3 samples)

2. Show MTB cells coloured

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12
Q

How does the chest radiography diagnosis work?

A
  1. Non specific
  2. Advanced TB
  3. White and shadowing bronchopneumonia lung infiltrations
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13
Q

How does the diagnosis of Tuberculin skin testing work?

A
  1. Mantoux test: intradermal injection and 48 to 72 hours later reveals erythema
  2. Measure the hard dense induction that’s raised and depending on it’s diameter it shows if you have latent TB
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14
Q

What is the T cell interferon Y release assay for the diagnosis of tuberculosis infection?

A
  1. Over night incubation of blood
  2. Insert into ELISA reader to display graph
  3. Isolate peripheral blood mononuclear cells
  4. Effector memory cells rapidly release interferon Y upon antigen contact
  5. Visualise underneath microscope to identify TB
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15
Q

Where are M. Tuberculosis populations most likely to reside in the body, in what type of environments and why?

A
  1. Open pulmonary cavities:
    - Plenty of oxygen
    - Rapid growth
    - Drug resistance develops
  2. Closed lesions in the lung
    - Oxygen starved
    - Limited penetration of drug
  3. Intracellular
    - Low pH
    - Drug may be inactive
    - Lack of oxygen
    - Slow and intermittent growing bacilli
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16
Q

What is the first line pharmacological management of TB?

A

Initial 2 month treatment:

  1. Isoniazid
  2. Rifampicin
  3. Pyrazinamide
  4. Ethambutol

Continuation 4 month treatment:

  1. Rifampicin
  2. Isoniazid
17
Q

How does Isoniazid work and its effect?

A
  1. Inhibits biosynthesis of mycolic acids constituents of mycobacterial cell wall
  2. Prodrug (depends on this to work): activated by bacterial catalase
  3. Metabolised by acetylation
  4. Effect:
    - Bacteriostatic for resting bacilli
    - Bactericidal for extracellular dividing microorganisms
18
Q

What are the adverse reaction patients on Isoniazid have?

A
  1. Peripheral neuropathy
  2. Autoimmune phenomena and blood disorders: anaemia
  3. Hepatotoxicity
19
Q

How does Rifampicin work?

A
  1. Inhibits DNA dependent RNA polymerase of mycobacteria
  2. Orally active
  3. Effects:
    - Bactericidal effect on 3 MTB population
20
Q

What are the side effects and adverse effects of Rifampicin?

A
  1. Orange and red coloration of urine and other body fluids
  2. Adverse effect:
    - Hepatotoxicity
    - Toxic syndrome
  3. Many drug interaction:
    - Rifampicin induces hepatic metabolising enzymes
    - Increased degranulation of warfarin
    - Glucocorticoids
    - Analgesic
    - Oestrogen
  4. Rapid development of resistance
21
Q

How does Ethambutol work?

A
  1. Mechanism of action:
    impairs biosynthesis
  2. Orally active
  3. Effects:
    bacteriostatic (selective for mycobacteria)
22
Q

What are the adverse effects of Ethambutol?

A

Adverse effects: uncommon

  1. Optic neuritis:
    - Changes in colour vision or visual field (reversible)
  2. Children use it with care as they cannot describe a change in vision
23
Q

How does pyrazinamide work, the effect and side effects?

A
  1. Involves metabolism of drug within bacteria to produce toxic product
  2. Effect:
    - Inactive at neutral pH but bacteriostatic at acidic pH
    - Affects intracellular mycobacteria
  3. Resistance develops rapidly
  4. Side Effects:
    Hepatotoxicity
    Increased plasma urate (gout)
24
Q

What is Rifater?

A

Combination of rifampicin: isoniazid: pyrazinamide treatment

25
Q

What is Rifinah?

A

Combination of rifampicin: isoniazid

26
Q

How is multi-drug resistance managed?

A
  1. Individualised treatment
  2. Complex regimen
  3. Multiple reserve drugs
27
Q

How is TB vaccinated?

A

BCG vaccination

28
Q

What does BCG contain and what protection does it provide?

A
  1. Live weakened M.Bovis form of TB
  2. Gives 60-80% protection against TB in childhood
  3. Loses efficacy in adult hood

PM2C: Therapeutics and Patient Care: Summer (25 decks)

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