Pathology of Respiratory Tract Infections Flashcards

1
Q

What are different kinds of microorganisms in terms of pathogenecity?

A

Primary

Facultative

Opportunistic

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2
Q

What are primary microorganisms?

A

Can establish an infection in almost anyone

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3
Q

What are facultative microorganisms?

A

Requires defences to be reduced a little bit to cause disease

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4
Q

What are opportunistic microorganisms?

A

Not very infectious, do not have pathogenic properties to invade human tissue, but if defences are dropped then they can cause a clinically evident infection

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5
Q

What does the ability to resist infection depend on?

A

State of the host defence mechanism

Age of patient

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6
Q

What are some upper respiratory tract infections?

A

Coryza (common cold)

Sore throat syndrome

Acute laryngotracheobronchitis (coup)

Laryngitis

Sinusitis

Acute epiglottitis

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7
Q

What is the common cold also known as?

A

Coryza

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8
Q

What is coup also known as?

A

Laryngotracheobronchitis

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9
Q

What is acute epiglottis commonly caused by?

A

Group A beta haemolytic streptococci

Haemophilus influenza

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10
Q

Who seems to be most prone to acute epiglottitis?

A

Young children

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11
Q

What are some examples of lower respiratory tract infections?

A

Bronchitis

Bronchiolotis

Pneumonia (acute inflammatory process in the alveoli)

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12
Q

What is pneumonia?

A

Acute inflammatory process in the alveoli

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13
Q

What are some respiratory tract defence mechanisms?

A

Macrophage-mucociliary escalator system

General immune system

Respiratory secretions

Upper respiratory tract as a filter

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14
Q

What is the macrophage-mucociliary escalator system composed of?

A

Alveolar macrophages

Mucociliary escalator

Cough reflex

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15
Q

How does the upper respiratory tract help to prevent the lower respiratory tract from becoming infected?

A

Warms and humidifies air, supplying a large surface area where material in the air may be deposited so it does not reach the lower respiratory tract

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16
Q

How are particles cleared from the lungs?

A

Macrophage-mucociliary escalator:

1) Macrophages clear particles by phagocytosis
2) Leave via the muco-ciliary escalator or through lymph

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17
Q

What is pneumonia classified by?

A

Anatomical (understand radiology)

Aetiological (how acquired, such as from a hospital or community)

Microbiology (tells us how to treat the patient)

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18
Q

What are some different aetiological classifications of pneumonia?

A

Community acquired

Hospital acquired (nosocomial)

Pneumonia in the immunocompromised

Atypical pneumonia (caused by unusual organism)

Aspiration pneumonia

Recurrent pneumonia

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19
Q

What is a hospital acquired infection also known as?

A

Nosocomial infection

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20
Q

What are infections from hospital more likely to be?

A

Resistant to antibiotics

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21
Q

What are some different patterns of pneumonia?

A

Bronchopneumonia

Segmental

Lobar

Hypostatic

Aspiration

Obstructive, retention, endogenous lipid

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22
Q

What is hypostatic pneumonia?

A

Patient has some other pathological process that lead to the accumulation of fluid in the lung, such as cardiac failure with chronic edema

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23
Q

What occurs in bronchopneumonia?

A

Acute inflammation

Pus from polymorphs replaces air

Accumulation of neutrophils in alveolar space

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24
Q

What is the infected site in segmental and lobar pneumonia normally like?

A

Unilateral in a single site or area of the lung which is infected

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25
Q

How does segmental and lobar pneumonia differ from bronchopneuonia?

A

Segmental and lobar are at a single site whereas broncho is multilocal

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26
Q

What is bronchopneumonia characerised by?

A

Spots of infection stay around alveoli

Rare for infection to reach the pleura

Basal parts of the lungs infected

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27
Q

What is lobar pneumonia characterised by?

A

Large amount of lung infected by the same inflammatory process

Could be an entire lobe

Meaning the whole part is airless due to being filled with pus

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28
Q

What kind of pneumonia could lead to a pleural infection?

A

Lobar, pleural infections are rare with bronchopneumonia

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29
Q

What are possible outcomes of pneumonia?

A

Most resolve

Pleurisy, pleural effusion and emphysema

Organisation

Lung abscess

Bronchiectasis

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30
Q

What are examples of pneumonia leading to organisation?

A

Mass lesion

Cryptogenic organising pneumonia (COP)

Constructive bronchiolotis

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31
Q

What could pneumonia lead to instead of resolution?

A

Fibrosis

Abscess (infected area dies which creates a hole in the lung)

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32
Q

What can the outcome of pneumonia mimic?

A

Can result in a lump which mimics cancer, only to realise it is not cancer once it has been removed

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33
Q

What is a lung abscess?

A

Necrosis of the lung and formation of a cavity

34
Q

What causes a lung abscess?

A

Necrotic lung (2nd degree infection)

Particular organisms

Obstructed bronchus (tumour)

35
Q

What can a lung abscess lead to?

A

Blood poisoning (pyaemia)

36
Q

What is pyaemia?

A

A type of septicaemia that leads to widespread abscesses (blood poisoning)

37
Q

What is bronchiectasis?

A

Pathological dilation of bronchi

38
Q

What can bronchiectasis be due to?

A

Severe infective episode

Recurrent infections

Proximal bronchial obstruction

Lung parenchymal destruction

39
Q

What is parenchyma?

A

The functional tissue of an organ

40
Q

What is the functional tissue of an organ called?

A

Parenchyma

41
Q

In basic terms, what is bronchiectasis?

A

Increase in the diameter of the airways relative to its position

42
Q

When does bronchiectasis usually start?

A

75% of the time in childhood

43
Q

What are symptoms of bronchiectasis?

A

Cough

Abundant purulent foul sputum

Haemoptysis

Signs of chronic infection

Coarse crackle, clubbing

44
Q

What is haemoptysis?

A

Coughing up blood

45
Q

What is coughing up blood called?

A

Haemoptysis

46
Q

What is bronchiectasis diagnosed by?

A

Thin section

CT

47
Q

What is the treatment of bronchiectasis?

A

Postural drainage

Antibiotics

Surgery

48
Q

Is bronchiectasis usually localised or widespread?

A

Widespread

49
Q

When can bronchiectasis be removed?

A

When it is localised

50
Q

What do we need to consider in recurrent lung disease?

A

Why the defences are failing

51
Q

What can we ask when considering why the defences are failing?

A

Local bronchial obstruction (tumour, foreign body)?

Local pulmonary damage (bronchiectasis)?

Generalised lung disease (cystic fibrosis, COPD)?

Non-respiratory disease (immunocompromised, aspiration)?

52
Q

What may aspiration pneumonia be due to?

A

Vomiting

Oesophageal lesion

Obstetic anaesthesia

Neuromuscular disorders

Sedation

53
Q

What are opportunistic infections?

A

Infections by organisms not normally capable of producing disease in patients with intact lung defences

54
Q

What are some examples of opportunistic pathogens?

A

Low grade bacterial pathogens

Cytomegalovirus (CMV)

Pneumocystis jirovecii

Other fungi and yeasts

55
Q

What are the 2 things flow of air can be?

A

Laminar or turbulent

56
Q

What is laminar flow?

A

Ordered

57
Q

What is ordered flow known as?

A

Laminar

58
Q

What is turbulent flow?

A

Random or chaotic

59
Q

What is random or chaotic flow known as?

A

Turbulent flow

60
Q

What does bulk flow depend on?

A

Pressure difference

61
Q

What occurs beyond the terminal bronchiole?

A

Diffusion

62
Q

What barrier is present in the alveoli?

A

Blood air barrier

63
Q

What is the normal PaO2 value?

A

10.5-13.5kPa

64
Q

What is the normal PaCO2 value?

A

4.8-6kPa

65
Q

What are the 2 kinds of respiratory failure?

A

Type 1

Type 2

66
Q

What is type 1 respiratory failure?

A

PaO2 < 8kPa, PaCO2 normal or low)

67
Q

What is type 2 respiratory failure?

A

PaCO2 > 6.5kPa, PaO2 usually low

68
Q

What are 4 abnormal states associated with hypoaemia?

A

Ventilation/perfusion imbalance (V/Q)

Diffusion impairment

Alveolar hypoventilation

Shunt

69
Q

What is hypoxaemia?

A

Low levels of oxygen in the blood

70
Q

What is low levels of oxygen in the blood known as?

A

Hypoxaemia

71
Q

What happens when alveolar oxygen tension falls?

A

Pulmonary arteriolar vasoconstriction occurs so blood is not sent to alveoli short of oxygen

72
Q

What happens if there is arterial hypoxaemia?

A

All vessels constrict

73
Q

What is the size of a normal breath?

A

4L

74
Q

What is the normal cardiac output?

A

5L

75
Q

What is the normal ventilation/perfusion (V/Q) value?

A

0.8

76
Q

What is the commonest cause of hypoxaemia?

A

Low V/Q

77
Q

What does a low V/Q in some alveoli arise due to?

A

Local alveolar hypoventilation due to some disease

78
Q

What is shunt?

A

Blood passes from right to left side of the heart without contacting ventilated alveoli

79
Q

What is it called when blood travels from the right to the left side of the heart without contacting ventilated alveoli?

A

Shunt

80
Q

How do large shunts respond to increases in FIO2?

A

Poorly because the blood leaving the lung is already 98% saturated (no level of oxygen can oxygenate the blood because it cannot be passed onto the blood)

81
Q

What is FIO2?

A

The fraction of inspired air which is oxygen

82
Q

What is the normal value of FIO2?

A

0.21