POM 14 - Patient with tuberculosis

Question 1

what are the 2 main classifications of mycobacteria

Answer 1

TB

non tuberculous mycobacteria

Question 2

what are the 3 types of non tuberculous mycobacteria

Answer 2

rapid growing

non rapid growing

other

Question 3

what disease can non tuberculous mycobacteria cause

Answer 3

leprosy

Question 4

how does TB enter the body

Answer 4

breathing in TB particle and TB lands in nose or lungs

Question 5

TB will cause disease if it lands in what anatomy - why is this

Answer 5

if it lands in lungs

TB wants to be eaten by lung macrophage

Question 6

what is a lung macrophage called

Answer 6

pulmonary alveolar macrophage

Question 7

what happens when TB is phagocytosed by lung macrophage

Answer 7

LAM on surface of TB binds to complement receptor of pulmonary macrophage

LAM makes TB preferentially phagocytosed by pulmonary macrophages

Question 8

what happens when lysosomes attempt to kill TB

Answer 8

TB resists

Question 9

how does TB survive intracellularly

Answer 9

changes cellular function by stopping apoptosis and induces macrophage to stay alive

Question 10

what does the immune system do once the TB survives in the macrophages

Answer 10

takes antigen producing cells and macrophages taken antigen to the lymph nodes and find helper T cells which recognize Tb and recruits other cell

overall TB is carried to the local lymph nodes

Question 11

how does the immune system ‘quarantine’ the bacteria infected cells

Answer 11

via a granuloma

puts uninfected macrophages around infected cell - forms ball around gooey necrotic centre

Question 12

when the granuloma has been put in place around the TB cells how is the granuloma sustained

Answer 12

helper T cells form sphere around outside to continuously bombard macrophage jail with signals to keep their integrity and keep them alive/robust

Question 13

what can happen with latent TB infections

Answer 13

can be reactivated if something upsets the immune system and the granuloma can fall apart to spread TB

Question 14

what is the primary cytokine the helper T cells use to bombard the granuloma

Answer 14

tumor necrosis factor alpha (TNFa)

Question 15

what is miliary TB

Answer 15

TB which has disseminated everywhere

Question 16

what are the 7 outcomes of primary TB infection

Answer 16

focus

pleural

cavitation

enlarged nodes

TB bronchopneumonia

pericardial disease

miliary

Question 17

what is ghons focus outcome in primary TB infection

Answer 17

calcium in lungs/lymph node

Question 18

what is pleural outcome in primary TB infection

Answer 18

Tb on periphery of lungs and alveoli bursts

Question 19

what is cavitation outcome in primary TB infection

Answer 19

abscess where the granuloma eats away at the lung tissue

a variant of pulmonary Tb

Question 20

what is enlarged nodes outcome in primary TB infection

Answer 20

enlarged lymph nodes which squashes the airways

Question 21

what is pericardial disease outcome in primary TB infection

Answer 21

TB sitting next to heart and erodes through heart and explodes causing infection in pericardium

this infection then goes onto squish the heart and impede heart function

Question 22

how is TB transmitted

Answer 22

droplet and airborne transmissions

cutaneous and gastrointestinal tract from drinking milk used to be as well but not anymore

Question 23

how is TB diagnosed - 4 ways

Answer 23

chest xray - but is non specific

sputum specimens via acid fast bascillus

TB PCR to find DNA of TB

TB culture

Question 24

how is the ziehl neelsen stain performed for TB - 4 steps

Answer 24

1. smear specimen on slide
2. apply carbo-fuchsin stain
3. apply heat
4. wash with HCl in ethanol

Question 25

how does the ziehl neelsen stain identify mycobacteria from other bacteria

Answer 25

mycobacteria retains the stain which is incorporated into the lipid cell wall - the stain is trapped in TB after being solidified and cooled

most other bacteria lose the stain

Question 26

how can we diagnose latent TB

Answer 26

can detect if immune system knows about TB

use interferon gamma release assay - QuantiFERON gold test

Question 27

how is interferon gamma release assay/QuantiFERON gold test performed - 3 steps

Answer 27

1. whole blood incl WBC into test tube
2. add mitogen to make lymphocytes proliferate - if immune system WBC have seen TB before then it will release interferon gamma
3. add TB antigens - they will proliferate and release interferon gamma if person has been exposed to TB in the past