TB Flashcards

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1
Q

population infected with TB

A

1/3 of the population

rate of new TB cases falling globally

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2
Q

TB description

A

chronic, granulomatous disease caused by the bacterium mycobacterium tuberculosis

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3
Q

TB caused by

A

Mycobacterium tuberculosis

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4
Q

mycobacterium tuberculosis

A

phagocytksed by macrophages an dis found in membrane bound particles known as phagosomes

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5
Q

infected phagosomes

A

does not mature to fuse with lysososomes/acidity

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6
Q

granuloma formation

A

body contains intracellular mycobacterium tuberculosis within macrophages

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7
Q

transmission of TB

A

aerosol transmission occurs from persons with infectious active TB disease
spread by droplet nulclei

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8
Q

droplets of TB

A

remain suspended for long periods

expelled when a person with infectious TB coughs, sneezes, speaks or sings

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9
Q

after environmental exposure

A

70% uninfected

30% infected

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10
Q

after infected with TB

A

5-10% primary tuberculosis

90-95% latent TB infection

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11
Q

after latent infection established

A

containment and persistence

a portion will develop reactivation disease

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12
Q

risk factors for developing reactivation disease

A

10% healthy adults
20% children <5 years
30% HIV+ patients
40% children <2 years

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13
Q

ghon complex

A

peripheral lesion and casiating lymph nodes
majority will heal lesion and remain asymptomatic, some will develop latent infection, some will develop progressive primary tuberculosis

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14
Q

reactivation of latent TB

A

secondary tuberculosis

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15
Q

secondary tuberculosis

A

localised caveating destructive lesions or progressive secondary TB

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16
Q

miliary Tb

A

massive haematogenous dissemination from progressive primary or secondary TB

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17
Q

TB & HIV

A

deadly synergy

- HIV infection promotes progression of TB infection to active disease

18
Q

risk for developing TB for HIV negative

A

10% lifetime risk

19
Q

risk for developing TB for HIV positive

A

10% annual risk

leading cause of death in those with HIV infection

20
Q

preventing TB in HIV positive cases

A

preventative therapy - isoniazid or combination isoniazid with rifampicin

21
Q

TB and poverty

A

increased risk of exposure
increased risk of disease after infection
less chance of being. diagnosed and of receiving effective treatment

22
Q

clinical manifestations of TB

A
  • lungs
  • pleura
  • CNS
  • lymphatic system
  • genitourinary system
  • bones and joints
  • disseminated
23
Q

pulmonary TB symptoms

A

pulmonary TB

  • productive prolonged cough
  • chest pain
  • haemoptysis
24
Q

systemic TB symptoms

A
  • fever, chills, night sweats, loss of appetite, weight loss, fatigue
25
Q

TB diagnosis

A
  • medical history and physical examination
  • chest x ray
  • tuberculin skin test or IGRA
  • sputum sweat microscopy
  • bacteriological culture
  • molecular diagnosis
26
Q

chest x-ray

A

early abnormalities are hard to see
upper lobe cavities
HIV infected patients and children less commonly have cavities

27
Q

tuberculin skin testing

A

intradermal infection of PPD (purified protein from TB) into forearm
- measure diameter of induration (swelling) 48-72 hours later

28
Q

tuberculin skin test is positive if

A

> 5mm in HIV infected

>10mm in HIV-free

29
Q

problems with tuberculin skin test

A

false positives - BCG, environmental mycobacteria

false negatives - immune suppression, advanced TB

30
Q

interferon gamma release assays

A

an in vitro version of the skin test
Quantiferon
stimulate whole blood from patients with TB antigensand measure release of IFN

31
Q

benefit of interferon gamma release assay

A

more specific/convenient

but costly

32
Q

sputum smear microscopy

A

sputum is concentrated, smeared on a slide, stained and an acid fast stain and viewed under a microscope
cheap and does not require sophisticated laboratories
low sensitivity

33
Q

mycobacterial culture

A

culture from sputum or other samples
takes a long time and requires sophisticated labs
biosafety risk to staff

34
Q

molecular diagnsosis

A

minultaneously detects presence of TB and resistance to rifampicin
more sensitive than smear microscopy

35
Q

urine LAM

A

lipoarabinomannan
TB found in urine of patients
best in patients with HIV
insensitive test

36
Q

BCG vaccination

A

can be given pre and post exposure
live attenuated version of Mycobacterium Bovis
reduces incidence and severity in children
inconsistent results for adults

37
Q

INH preventive treatment

A

prevent from progressive from latent to active TB

38
Q

TB treatment

A

need to treat with multiple drugs - to prevent emergence of reistant strains
minimum treatment duration is 6 months fro drug sensitive TB
- slow growing bacertium which develops tolerance to drugs - not all bacteria are killed by drug exposure

39
Q

multidrug resistant is resistant to

A

isoniazid and rifampicin

40
Q

extensively drug resistant TB

A

resistance to injectable drugs

41
Q

TB infection prevention control

A

cohort or isolate patients