Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Respiratory > TB > Flashcards

TB Flashcards

1
Q

What are the demographics and risk factors of TB?

A
  • Non-UK born/recent migrants especially from South Asia and sub-Saharan Africa
  • HIV and other immunocompromised conditions
  • Homelessness
  • Drug use, prisoners
  • Close contacts
  • Young adults/elderly
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which organisms cause TB?

A
  • Mycobacterium tuberculosis (primary cause in humans)
  • Mycobacterium bovis
  • Mycobacterium africanum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Outline the structure of mycobacterium

A
  • Non-motile
  • Rod shaped
  • Obligate aerobe
  • Long-chain fatty (mycolic) acids, complex waxes and glycolipids in cell wall
  • Gives structural rigidity, staining characteristics, acid alcohol fast
  • Relatively slow-growing compared to other bacteria (generation time 15-20 hours)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How is TB spread?

A
  • Respiratory droplets from coughing, sneezing etc
  • Droplet nuclei suspended in air
  • Reach lower airway
  • Contagious but not easy to acquire infection
  • Difficult to acquire TB from casual contact
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the infectious dose of TB?

A
  • 1-10 bacilli
  • Prolonged exposure facilitates transmission (at least 8 hours/ day for up to 6 months)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Outline the pathogenesis of TB

A
  • Inhaled aerosols
  • Engulfed by alveolar macrophages
  • Local lymph nodes
  • Primary complex (Ghon’s focus and draining lymph nodes)
  • Only 5% of cases progress to active disease - primary
  • Rest of infections are initially contained
  • Latent infection
  • 95% of latent infections heal/self-cure
  • 5% reactivate and cause post primary TB
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does post primary TB occur?

A
  • Reactivation of bacteria can occur at any point
  • Multiply, cause infection, and damage host tissues
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are risk factors for reactivation of TB?

A
  • HIV infection
  • Substance abuse
  • Prolonged therapy with corticosteroids
  • Immunosuppressive therapy
  • Organ transplant
  • Diabetes mellitus
  • Severe kidney disease
  • Organ transplant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Outline latent TB infection

A
  • Inactive, contained bacilli in body
  • TST or IFN gamma test results usually positive
  • CXR normal
  • Negative sputum smears and cultures
  • No symptoms
  • Not infectious
  • Not a case of TB
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Outline TB disease

A
  • Active multiplying bacilli in body
  • TST or blood test results usually positive
  • CXR abnormal
  • Sputum smears and cultures may be positive
  • Symptoms such as cough, fever, weight loss
  • Often infectious before treatment
  • A case of TB
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the site of pulmonary TB?

A
  • Lungs
  • Most TB cases are pulmonary
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the sites of extrapulmonary TB?

A
  • Larynx
  • Lymph nodes
  • Pleura
  • Brain
  • Kidneys
  • Bones and joints
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Who is more commonly affected by extrapulmonary TB?

A
  • HIV-infected people
  • Immunosuppressed people
  • Young children
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is miliary TB?

A
  • Carried to all parts of body through bloodstream
  • Rare
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What pathology can be seen in biopsy of a patient with TB?

A
  • Caseating granulomata
  • Central necrosis, fibrin, exudate, dead and dying immune cells
  • Surrounded by rich collection of immune cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What clinical approach should we take when suspecting a patient has TB?

A
  • Index of suspicion
  • Detailed history and examination
  • Investigate
  • Treat
  • Prevent onward transmission
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

When might we suspect someone has TB?

A
  • Non-UK born
  • Recent migrants from high risk countries
  • HIV
  • Immunocompromised states
  • Homeless, drug users, prison inmates
  • Close contacts of patients with TB
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the symptoms of TB?

A
  • Fever
  • Night sweats
  • Weight loss and anorexia
  • Tiredness and malaise
  • Cough
  • Haemoptysis
  • Breathlessness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the signs of TB on examination?

A
  • Often no chest signs despite CXR abnormality
  • Maybe crackles in affected area
  • In extensive disease: signs of cavitation and fibrosis
  • If pleural involvement: typical signs of effusion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What tests are done to investigate pulmonary TB?

A
  • CXR (mainstay of diagnosis)
  • Samples for microbiology: sputum
  • Histology i.e. of a lymph node
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What sputum samples are taken to investigate TB?

A
  • 3 early morning samples (minimum volume 5ml)
  • Induced sputum
  • Broncho-alveolar lavage fluid (patients with a dry cough)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What radiological findings are seen in pulmonary TB?

A
  • Apex of lung often involved
  • Ill defined patchy consolidation
  • Cavitation usually develops within consolidation
  • Healing results in fibrosis
  • Pleural TB - pleural effusion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Outline TB microscopy

A
  • Mainstay of TB diagnosis worldwide
  • 2 staining methods
  • Rapid and cheap
  • Not very sensitive
  • Measures infectiousness - a smear positive case is infectious
  • Cannot differentiate MTB from NTM
  • Cannot differentiate live and dead organisms
24
Q

What is the gold standard of TB diagnosis?

A
  • TB culture
  • Most sensitive method for detecting mycobacteria
  • Different culture methods/media
  • Solid and liquid culture systems
  • Automated culture technology - improves isolation of TB bacilli
  • Allows identification and susceptibility testing
25
Q

How are nucleic acid detection tests used to diagnose TB?

A
  • Rapid diagnosis
  • Drug resistance mutations
  • Whole genome sequencing for culture isolates
  • Species identification
  • Drug susceptibility
26
Q

How is latent TB diagnosed?

A
  • Tuberculin sensitivity test
  • Interferon Gamma Assays
  • Interferon Gamma Releasing Assays
27
Q

How does tuberculin sensitivity testing works?

A
  • Measures cell mediated immune response
  • In form of delayed type hypersensitivity to purified protein derivative of M tuberculosis
28
Q

How is tuberculin skin testing carried out?

A
  • Tuberculin injected intradermally
  • Results taken 48-72 hours later
  • Subjective interpretation
29
Q

How accurate is tuberculin skin testing?

A
  • False positives (BCG, Non TB mycobacteria)
  • False negatives (immunocompromised i.e. HIV/ drugs/ advanced disease)
30
Q

What are the pros/cons of tuberculin skin testing?

A
  • Cheap
  • Laboratory infrastructure not required
  • Evidence to predict progression to active disease
31
Q

How do interferon gamma assays work?

A
  • In vitro test
  • T cell based assay
  • Measures interferon gamma
32
Q

How do interferon gamma releasing assays work?

A
  • Detection of antigen specific IFN-gamma production
  • T spot TB assay
  • Quantiferon TB gold plus
  • No cross-reaction with TB
33
Q

What are the first line medications for TB?

A
  • Rifampicin
  • Isoniazid
  • Pyrazinamide
  • Ethambutol
34
Q

What are the second line medications for TB?

A
  • Quinolones (moxifloxacin)
  • Injectables (capreomycin, kanamycin, amikacin)
  • Ethionamide/Prothionamide
  • Cycloserine
35
Q

What are the principles of TB treatment?

A
  • Early and adequate treatment with anti TB drugs (make patient non-infectious)
  • Close monitoring of compliance
  • Prevent secondary transmission and cases
36
Q

Why is TB treated with multi-drug therapy?

A
  • When TB multiply there are mutations
  • Long treatment course means mutations are more likely to happen before TB is eradicated
  • Using multiple drugs reduces likelihood of resistance
37
Q

What effects does rifampicin have on the body?

A
  • Raised transaminases
  • Induces cytochrome P450
  • Orange secretions/urine
38
Q

What effects does isoniazid have on the body?

A
  • Peripheral neuropathy
  • Hepatotoxicity
39
Q

What effects does pyrazinamide have on the body?

A
  • Hepatotixicity
40
Q

What effects does ethambutol have on the body?

A
  • Visual disturbance
41
Q

Other than medication, what is used to treat TB?

A
  • Vitamin D
  • Surgery
42
Q

What is the duration of TB treatment like?

A
  • 3 or 4 drugs for two months
  • Then rifampicin and isoniazid for four months
  • 18 month treatment if CNS TB
  • Cure rate is 90%
  • Compliance is a big problem
  • Side effects for a long period of time
43
Q

How do we ensure adherence to TB treatment?

A
  • Directly observed therapy
  • Video observed therapy
44
Q

Outline how drug resistance develops and spreads

A
  • During multiplication, a small number of naturally drug resistant organisms arise through spontaneous mutations
  • Improper drug regimens/poor drug compliance leads to selection of these mutants
  • Single and multi drug resistance
45
Q

What makes development and spread of drug resistance more probable?

A
  • Diagnostic delays
  • Overcrowding
  • Inadequate infection control facilitates transmission of drug resistance
  • Previous TB infection
  • HIV +
  • Known contact of MDR TB
46
Q

What is multi-drug resistant TB?

A
  • Resistant to rifampicin and isoniazid
47
Q

What is extremely drug resistant TB?

A
  • Also resistant to fluoroquinolones and at least 1 injectable
  • As well as rifampicin and isoniazid
48
Q

Outline miliary tuberculosis in detail

A
  • Bacilli spreading through bloodstream
  • Widespread infection
  • Either during primary infection or reactivation
  • Lungs always involved
  • Often multiple organs involve
49
Q

Which other organs can be affected by miliary TB?

A
  • Headaches suggest meningeal involvement
  • Pericardial, pleural effusions
  • Ascites (involvement of peritoneum)
  • Retinal involvement
  • Lungs are always involved - fever, very unwell, dry cough
50
Q

What is lymphadenitis?

A
  • Extra-pulmonary TB common in children
  • Scrofula
  • Cervical lymph nodes most commonly affected
  • Abscesses and sinuses
51
Q

What other areas of the body can be affected by extra-pulmonary TB?

A
  • Gastrointestinal (due to swallowing of tubercles)
  • Peritoneal (ascitic or adhesive)
  • Genitourinary (slow progression to renal disease and subsequent spread to lower urinary tract)
  • Bone and joint via haematogenous spread (spinal TB or Pott’s disease)
52
Q

What are the symptoms of tuberculous meningitis?

A
  • Chronic headache
  • Fevers
  • CSF contains markedly raised proteins, lymphocytosis
53
Q

How is TB prevented?

A
  • TB cases must be notified to public health
  • Triggers contact tracing procedures
  • Provides surveillance data to detect outbreaks and monitor epidemiological trends
54
Q

How is TB controlled?

A
  • Infection control to prevent transmission
  • PPE
  • Negative pressure isolation
  • Reduce acquiring TB
  • Vaccination
55
Q

What vaccine is given against TB?

A
  • BCG
  • Live attenuated M. bovis strain
  • Given to babies in high prevalence communities only
  • 70-80% effectiveness in preventing severe childhood TB
  • Protection wanes
  • Little evidence protecting adults
56
Q

What are other indications for the BCG vaccine?

A
  • New entrants from high risk areas
  • Healthcare workers
  • Close contacts of active respiratory TB

Respiratory (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions