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Infect & Immune 1 JAL & MW > JAL L1 TB > Flashcards

JAL L1 TB Flashcards

1
Q

What organism is the cause of TB?

A

Mycobacterium tuberculosis

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2
Q

TB is a major opportunistic infection in whom?

A

AIDs patients, children

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3
Q

What caused the most dramatic decrease in TB numbers so far?

A

improvements in living conditions

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4
Q

what sort of thing is Mycobacterium tuberculosis

A

a slow growing bacillus

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5
Q

why is M. TB resistant to weak disinfectants?

A

cell wall is rich in lipids - very hydrophobic which prevents it drying out

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6
Q

There are 3 other strains that can cause TB:

A

M. bovis
M. africanum
M. microti

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7
Q

What happens when bacilli droplets are inhaled?

A

They are phagocytosed by macrophages, but this DOES NOT destroy them

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8
Q

Why can’t macrophages destroy TB?

A

It never fuses with the lysosome - we don’t know why, something to do with the bacterial cell wall

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9
Q

How long does TB sit in the macrophage? What is it doing there?
What happens next?

A

7-21 days
it’s MULTIPLYING.

The macrophage bursts

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10
Q

Macrophages are doing a terrible job of controlling the TB so who do we call?

A

GHOSTBUSTERS!

but actually T and B cells

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11
Q

What do T and B cells do to the TB?

A

form tubercles

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12
Q

How are tubercules formed?

A

fibroblasts come and lay down collagen fibres to contain the disease, macrophage dies off and you get a fatty deposit inside

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13
Q

Can you get rid of the tubercules?

A

no they stay for ever even if you no longer have the disease

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14
Q

What are the things that can happen once you get tubercules?

A

50% people clear the infection
some have latent infection - (dormant)
some get the progressive disease

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15
Q

How do we go from tubercle to infection?

A

Bacteria multiply in the macrophage - uncontrolled lysis releases them.

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16
Q

Bacteria does what to destroy tissues?

A

release enzymes

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17
Q

5 symptoms of TB

A 
night sweats
cough
blood in sputum
weight loss
afternoon fever
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18
Q

How to diagnose (4)

A

chest xray
tuberculin skin test
sputum test - culture takes weeks
DNA probe

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19
Q

can you use a gram stain?

A

no

20
Q

Can we immunise against TB?

A

yes- BCG vaccine for high risk groups

21
Q

criteria for anti-TB drugs?

A
  • intracellular activity
  • combination therapy
  • interaction with other anti-TB
  • prolonged therapy (so min s/e and low tox)
  • should treat distinct TB populations
22
Q

What are the 4 first line anti-TB drugs?

A

Rifampicin
Isoniazid
Pyrazinamide
Ethambutol

23
Q

is Rifamicin bacteriostatic or cidal?

A

Cidal

24
Q

is Rifampicin orally fully absorbed?

A

yes - but less with food

25
Q

s/e of rifampicin

A

liver damage
hypersensitivity
reduced activity of other drugs (e.g. COC)
red colour in bodily fluids

26
Q

is isoniazid bacteriostatic or cidal?

A

cidal or static prodrug

27
Q

how does isoniazid work?

A

reduces synthesis of mycolic acid (cell wall)

28
Q

is isoniazid given orally

A

usually yes but parenteral also available

29
Q

isoniazid well distributed?

A

yes - especially in the CSF

30
Q

where is isoniazid cleared

A

met in the liver, excret in the kid

31
Q

s/e of isoniazid

A

liver damage
hypersensitivity
reduced activity of other drugs (e.g. COC)
peripheral neuropathy

32
Q

is pyrazinamide bacteriostatic or cidal?

A

cidal (prodrug)

33
Q

how does pyrazinamide work?

A

reduces synthesis of mycolic acid/damages bacterial memebrane

34
Q

PK of pyrazinamide?

A

Oral well absorbed

met in the liver, excret in the kid

35
Q

s/e of pyrazinamide?

A

joint pain
liver damage
hypersensitivity

36
Q

Which is the only drug that can actually kill off dormant bacteria

A

pyrazinamide

37
Q

Is ethambutol static or cidal?

A

static

38
Q

how does ethambutol work?

A

increases permeability of the cell wall

39
Q

PK of ethambutol

A

orally well absorbed and 50% excreted unchanged into the urine

40
Q

s/e of ethambutol?

A

not for under 5s
joint pain
optic neuritis - reversible

41
Q

5 2nd line treatments

A 
streptomycin
capreomycin
cycloserine
ciprofloxacin
azithromycin
42
Q

What is the treatment schedule for active TB?

A

Rif & Isoniazid (6-9 months)

Pyrazin (2 months) & Ethan

43
Q

What is the treatment schedule for latent TB?

A

Treat pt on immunosupressants

Rif (6months) or Rif & Isoniazid (3 months)

44
Q

why long drug therapy?

A

dificult for drugs to penetrate tuburcules
rupture of legions causes renewed infection
Anti TB drugs only bacteriocidal against growing organisms

45
Q

Where does resistance come from?

A

poorly manage TB care

Infect & Immune 1 JAL & MW (12 decks)

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