Tuberculosis

Question 1

which pathogen causes tuberculosis?

Answer 1

mycobacterium tuberculosis

Question 2

how many people are infected with tb worldwide?

Answer 2

2 billion

Question 3

do all people with tb have symptoms?

Answer 3

no: 90-95% aren’t aware they are infected

Question 4

infected with tb but no symptoms: what is this called?

Answer 4

latent infection

Question 5

latent tb: what are risk factors to develop active disease? (2)

Answer 5

aids, old age

Question 6

what type of bacterium is tb: shape? aerobe/anearobe?

Answer 6

rod shaped
strictly aerobe

Question 7

how is tb transmitted?

Answer 7

inhalation

Question 8

how does tb survive inside a phagocyte in the alveoli?

what is the consequence?

Answer 8

after phagocytosis they prevent fusion with lysosomes

they can proliferate and cause localized infection

Question 9

what is primary tuberculosis? what are the symptoms?

Answer 9

localized infection after exposure

asymptomatic or flu-like symptoms

Question 10

what type of necrosis can form inside the granuloma?

Answer 10

caseous necrosis (also called ‘Ghon focus’)

Question 10

which 2 components make up the characteristic Ghon complex of tb?

Answer 10

Ghon focus (caseous necrosis inside granulomas) + hilar lymph nodes (also caseous necrosis inside)

Question 10

what can form inside the lungs +/-3 weeks after exposure? why is this?

Answer 10

granulomes

due to cell-mediated immunity: cells wall of the infection and prevent from spreading

Question 11

what can you see on chest x-ray of tb?

Answer 11

primary tb: enlarged hilus, consolidation
healed primary tb: Ghon focus (round, well-defined calcific density in the periphery)
reactivated tb: consolidations upper lobes

Question 11

what happens eventually to the granulomas, what type of tissue forms?

Answer 11

fibrosis + calcification

Question 12

which 2 directions can TB go after granuloma formation?

Answer 12

-> tb killed of, end of disease
-> tb remains viable inside granuloma (dormant)

Question 13

what are risk factors for dormant tb to become reactivated?

Answer 13

aids or aging

Question 14

reactivation of dormant tb from inside granuloma: where in lung does tb prefer to spread? why is this?

Answer 14

upper lobes, greater oxygenation (tb is aerobe)

Question 15

reactivation of dormant tb: after spreading to other parts of the lungs, do more or less T cells get activated this time? why is this? what is the consequence?

Answer 15

more, because of memory cells

consequence: more caseous necrosis with cavitations

Question 16

what is the consequence of cavitating necrosis? (2 things)

Answer 16

tb can now disseminate into:
1) lungs -> pneumonia
2) vasular system -> systemic miliary tb

Question 17

which system can be affected in systemic miliary tb? (6)

Answer 17

• kidneys: pyuria (WBCs in urine)
• lumbar vertebrae: Potts disease
• meningitis
• addison’s disease
• hepatitis
• cervical lymphadenitis

Question 18

how can you test for tb?

Answer 18

• dermal test: mantoux test
• blood test: IGRA (interferon gamma release assay)

Question 19

how does a mantoux test work?

Answer 19

inject component of tb in skin: if person has been infected before -> small localized reaction in 48-72h

(bump has to be of certain size to be positive test)

Question 20

what does a positive mantoux test indicate?

Answer 20

if someone has been exposed to tb

doesn’t differentiate between active and latent disease

Question 21

what are 2 benefits or IGRA testing?

Answer 21

• only need to show up once
• unlikely to be positive from BCG vaccine

Question 22

is there a tb vaccine?

Answer 22

yes, BCG vaccine (in NL: BCG vaccination is offered to children if one or both parents are from a country where tb is prevalent)

Question 23

positive mantoux or IGRA: what is the next step?

Answer 23

chest x-ray to check for active disease

Question 24

what are symptoms that are indicative of active tb?

Answer 24

fever, night sweats, weight loss, coughing up blood

Question 25

what type of testing can you do during active tb?

Answer 25

sputum/BAL: culture, PCR, staining

Question 26

how do you treat latent infection of tb?

Answer 26

antibiotics: isoniazid for prolonged time (+/- 9 months)

Question 27

how do you treat active infection?

Answer 27

combination of drugs (isoniazid, rifampin, ethambutol, pyrazinamide) for months -> non-infectieus in weeks

Question 28

which patients are the most infectieus?

Answer 28

adults with reactivated TB

Question 29

how do you prevent spreading from a patient with reactivated tb?

Answer 29

negative pressure room, FFP2 masks

Question 30

what are MDR-tb and XDR-tb?

Answer 30

multiple drug resistance tb xtreme drug resistance tb

Question 31

what are 3 things that can make sure the tb is treated effectively?

Answer 31

- use multiple drugs together - make sure specific strain is treated - use for prolonged time

Question 32

what is the course of tb infection: from infection to dissemination?

Answer 32

- infection -> primary infection with mild/no symptoms - after 3 weeks: granuloma formation (caseous necrosis) -> latent disease - aids or old age -> reactivation -> cavitating necrosis -> dissemination -> pneumonia/systemic disease