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Respiratory System > Tuberculosis And Asthma > Flashcards

Tuberculosis And Asthma Flashcards

1
Q

What are the 3 most common bacteria associated with human TB??

A

Mycobacterium tuberculosis
Mycobacterium bovids
Mycobacterium africanum

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2
Q

Describe some features of mycobacterium tuberculosis

A

Non-motile
Rod-shaped
Obligate aerobe
Has a very thick layer of fatty acids, glycolipids etc
Need Acid-Fast stain (cannot stain with Gram stain)

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3
Q

Why does mycobacterium TB take a long time to culture?

A

Relatively slow growing bacteria
Generation time 15-20 hours
Takes a minimum of 2 weeks to culture

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4
Q

How is TB spread?

A 
Respiratory droplets (coughing/sneezing) 
Infectious dose is very low 
Air remains infectious for 30 minutes
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5
Q

Is it easy to catch TB?

A

No

Usually need prolonged exposure to catch it

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6
Q

What are the classic situations in which TB spreads?

A

Overcrowding situations:
Poor housing
Prisons
Homeless people

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7
Q

Describe the pathogenesis of TB

A

Inhaled aerosols/droplets
Engulfed by alveolar macrophages
Drainage of lung to local lymph nodes
Primary complex/focus of infection established
Progression to primary active disease or initial containment of infection to latent

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8
Q

What are the 2 outcomes of latent infection?

A

Heals/self cure

Reactivation of post-primary TB

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9
Q

What is the commonest type of TB?

A

Reactivation of latent to post-primary TB

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10
Q

Describe how tests for latent TB would appear

A

TST (mantoux) and IFN gamma tests would be positive
Chest x-ray normal
Sputum smears and cultures normal
Asymptomatic

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11
Q

What are the main symptoms of active TB

A

Cough
Fever
Weight loss

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12
Q

What is miliary TB?

A

TB disseminated wide into the body via the blood stream
(Tiny spots throughout lung fields on x-ray)
Rare

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13
Q

What are some of the risk factors for reactivation?

A 
HIV 
Substance abuse
Prolonged corticosteroid therapy 
Immunosuppressants 
TNF alpha antagonist 
Low body weight 
Organ transplant 
Haematological malignancy 
Severe kidney disease
Diabetes mellitus 
Silicosis
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14
Q

What are caseating granulomata in TB?

A

Lung parenchyma and lymph nodes
Liquified and cheesy looking material
Dead and dying bacilli and inflammatory cells
Langhan’s giant cells present

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15
Q

What are the common sites for extrapulmonary TB?

A 
Larynx 
Lymph nodes
Kidneys 
Pleura
Brain 
Bones and joints
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16
Q

What are some risk factors for TB

A 
Non-Uk born/recent migrants
HIV infected
Immunocompromised
Homeless
Drug users
Prisoners 
Close contacts of patients with TB 
Young adults
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17
Q

What Hx would suggest TB?

A 
Recent arrival/travel
Contacts with TB 
BCG vaccination?
Fever
Weight loss
Malissa
Anorexia
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18
Q

List some symptoms of pulmonary TB

A 
Fever
Night sweats 
Weight loss/anorexia 
Tiredness
Malaise
Cough 
Haemoptysis 
Breathlessness
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19
Q

What are some signs on examination of pulmonary TB?

A 
Fever
Often no chest signs 
CXR abnormality 
May be crackles in infected areas 
(Pleural involvement = dullness)
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20
Q

What investigations would you run for TB??

A

CXR
Sputum - 3 early morning samples
Induced sputum via physiotherapy
Bronchoscopy

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21
Q

What would you see on a CXR for TB?

A

Apex of the lung often involved
Ill defined patchy consolidation
Cavities can develop in consolidation
Healing results in fibrosis

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22
Q

Why are sputum smears not very good in diagnosing TB?

A

Not very sensitive
May only have a few bacilli in
Operator dependents

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23
Q

What is the gold standard investigation for diagnosis of TB?

A

Culture (but takes approximately 2 weeks)

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24
Q

What are epitheloid cells?

A

Activated macrophages

Can fuse together to form giant cells

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25
Q

Describe the tuberculin sensitivity test (TST)/mantoux

A

Look for latent TB
Challenge with an antigen previously exposed to
Infected intra-dermally
Inflammation, red circle appear at injection site
Read 2-3 days later
(Can get false positives and false negatives)

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26
Q

Describe interferon gamma releasing assays (IGRAs)

A

Buffer test for latent TB
Blood test
No cross reaction with BCG
Cannot distinguish between latent and active TB

27
Q

What is the first line medication for TB?

A 
4 first line medications:
Rifampicin 
Isoniazid 
Pyrazinamide 
Ethambutol
28
Q

What are some problems with Rifampicin?

A

Can give orange secretions (tears/urine)

Cannot take whilst on the contraceptive pill

29
Q

What is the bad side effect of ethambutol?

A

Can cause visual disturbance

30
Q

What are the second line drugs for TB?

A

Quinolones
Clofazamine
PAS
Ethionamide

31
Q

Why do we always use a combination of drugs to treat TB?

A

TB is notorious for producing mutations

Don’t want to select for a particular strain

32
Q

What is the minimum course of treatment for TB?

A

6 months

33
Q

What is scrofula?

A

A lymphadenitis
Disease with glandular swellings
Probably a form of TB

34
Q

Give some common clinical signs of extrapulmonary TB

A

Lymphadenitis
Ascites
Adhesions of peritoneum
Pott’s disease

35
Q

What is Pott’s disease?

A

A form of TB where disease is seen in the vertebrae

36
Q

Name some of the TB prevention methods

A

All forms of TB must be notified to public health
Personal protective equipment
Negative pressure isolation
Susceptible people vaccinated

37
Q

Describe BCG vaccine

A

Live vaccine
From mycobacterium bovis strain
Given to babies in high prevalence communities
70-80% effective

38
Q

What is asthma?

A

Chronic inflammatory disorder of the airways

Reversible airway obstruction caused by inflammation, bronchoconstriction and mucus

39
Q

Describe what happens during an asthma attack

A

Environmental trigger breathed in
Inflammation driven by TH2 cells
Type 1 hypersensitivity reaction (immediate)
Airway narrowing - SM contraction, mucus production and inflammatory cell infiltration

40
Q

Is asthma restrictive or obstructive?

A

Obstructive

41
Q

What would the FEV1/FVC look like in asthma?

A

Before treatment = FEV1 reduced, FVC normal

After treatment = FEv1 and FVC normal

42
Q

Why is it difficult to diagnose asthma?

A

There is no standardisation of type, severity, frequency, symptoms or investigation findings
(Everybody gets it differently)

43
Q

What are the reversible symptoms of asthma?

A

Wheeze
Breathlessness
Chest tightness
Cough

44
Q

What is a wheeze?

A

High pitched
Expiratory musical sound
From narrowed airways

45
Q

Describe the typical features of a cough due to asthma

A

Worse at night
Dry
Exercise induced
Non-productive

46
Q

Give some clinical signs of asthma

A 
Respiratory rate increase
Tracheal tug
Recession 
Nasal flaring 
Accessory muscle use
47
Q

Give some features of a typical Hx for asthma

A

Eczema, hay fever etc (atopy)
Smoker/smoking in home
Mould in home/live on farm/pets

48
Q

Describe the peak flow of an asthmatic patient

A

Varies over the day
Diurnal variation
Treatment stabilises this a lot
Should increase after inhaler use

49
Q

What do we measure with spirometry?

A

FEV1

FVC

50
Q

What do we do first for someone with suspected asthma?

A

Trial them on bronchodilators for 1 month then review

See if symptoms and peak flow gets better

51
Q

Give some prevention methods for asthma

A

Change pillows and bedsheets every few years
Fresh air
Stop smoking

52
Q

What is the approach to asthma treatment?

A

Step up, step down

Step up to other medications if getting worse or down to less if getting better

53
Q

What is the general progression of treatment for an asthmatic getting worse?

A

Short acting inhalers
+ steroid inhalers
Long acting inhalers
Specialist care

54
Q

How does a short acting beta agonist work?

A

Helps to relax smooth muscle

Quick relief

55
Q

When do people require a step up from short acting inhalers?

A

If using the inhaler more than 3 times a week

Or if nocturnal symptoms occur more than once a week

56
Q

How to steroid inhalers work?

A

Preventer
Reduces inflammation - inhibitors of inflammatory cells and mediators
Prevents attacks

57
Q

Describe the clinical features of a mild asthma attack

A 
Sats >92%
Pulse <110 
Resp rate <25
Speech normal 
Minimal wheeze 
PEFR >75% predicted
58
Q

Describe the clinical features of a moderate asthma attack

A 
Sats >92%
Pulse <110 
Resp rate <25
Speech normal wheeze +++ 
PEFR 50-75% predicted
59
Q

Describe the clinical features of a severe asthma attack

A 
Sats <92%
Pulse >110 
Resp rate >25 
Can't complete sentences
No wheeze 
PEFR 35-50% predicted
60
Q

How do you treat a severe asthma attack?

A

Give lots of salbutamol via a nebuliser

With a continuous stream of oxygen

61
Q

Describe the clinical features of a life threatening asthma attack

A 
Sats <92% (cyanosis)
Silent chest/poor expiratory effort
Altered consciousness 
Exhaustion 
PEFR 35% predicted
62
Q

Why do we sometimes need to give IV salbutamol?

A

Sometimes the mediation struggles to get through the thick layer of mucus when in an inhaler

63
Q

What is the treatment for a life threatening asthma attack?

A

Do the A-E assessment
Be aware they may go into cardiac arrest
Oxygen
Salbutamol nebulisers - back to back until airways open
IV access (need to cannulate ASAP) - salbutamol

Respiratory System (13 decks)

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