Pathology of Respiratory Infections Flashcards

1
Q

What are the opposing factors for lung infections?

A
  • Microorganism Pathogenicity
  • Capacity to resist infection
  • Whether or not the person is in the population at risk
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2
Q

What is microorganism pathogenicity?

A

The ability of the microorganism as a pathogen to estbalish an infection.

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3
Q

What are primary pathogens?

A

Pathogens that are highly invasive. They are able to establish infections in healthy people.

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4
Q

What are facultative pathogens?

A

Groups of organisms in the middle which aren’t particularly infectious but they just need a bit of assisstance to be able to esatblish an infection.

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5
Q

What are opportunistic pathogens?

A

They have low invasiveness, low infectivity, only affect immuocpromised people.

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6
Q

What does the capacity to resist infection depend on?

A
  • State of the patients defence mechanisms

- Age of the patient

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7
Q

What are common URTIs?

A
  • Coryza - common cold
  • Sore throat syndrome
  • Acute Laryngotracheobronchitis (Croup)
  • Laryngitis
  • Sinusitis
  • Acute epiglottis
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8
Q

What are the main infectants of acute epiglottis?

A
  • Haemophilus influenzae

- Group A beta-hemolytic streptococci

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9
Q

What are common LRTIs?

A
  • Bronchitis
  • Bronchiolitis
  • Pneumonia
  • Consequences
  • Possible Complications
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10
Q

What is Bronchiolitis?

A

Infection of the bronchioles

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11
Q

What are the Respiratory Tract Defence mechanisms?

A
  • Immune system (humoral and cellular)
  • Respiratory tract secretions
  • The upper respiratory tract acts as a filter
  • Macrophage - mucociliary escalator system
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12
Q

What is the - Macrophage - mucociliary escalator system?

A
  • Alveolar macrophages
  • Mucociliary escalator
  • Cough reflex
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13
Q

What is the cytopathic effect?

A

Intracellular pathogens infect particularly the epithelium of the respiratory tract and they damage the cells.

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14
Q

What happens to the mucociliary escalator function after the cytopathic effect?

A

It is lost

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15
Q

What is a very important risk during influenza in terms of morbidity and mortality?

A

Secondary bacterial infection

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16
Q

What are the main classifications of pneumonia?

A
  • Anatomical (helps understand radiology)
  • Aetiological (circumstances leading to pneumonia)
  • Microbiological (which organisms cause the infection)
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17
Q

What are the aetiological classifications of pneumonia?

A
  • Community-acquired
  • Hospital-acquired (Nosocomial)
  • Pneumonia in the immunocompromised
  • Atypical pneumonia
  • Aspiration pneumonia
  • Recurrent pneumonia
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18
Q

What types of organisms cause hospital-acquired pneumonia?

A

Drug resistant

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19
Q

What are atypical pneumonia?

A

It is caused by rare organisms or viruses.

20
Q

What is aspiration pneumonia?

A

It follows the aspiration into the lungs of food material.

21
Q

What is recurrent pneumonia?

A

When a patient has recurrent episodes of pneumonia.

22
Q

What are the patterns of pneumonia?

A
  • Bronchopneumonia
  • Segmental pneumonia
  • Lobar pneumonia
  • Hypostatic pneumonia
  • Aspiration pneumonia
  • Obstructive, retention
23
Q

What is segmental pneumonia?

A

When a subpart of one lobe is affected by pneumonia.

24
Q

What is lobar pneumonia?

A

When one or more lobes is totally affected by the infection.

25
Q

What is hypostatic pneumonia?

A

The localisation of the infectious process in the lower parts of the lungs and relates to other diseases like cardiac failure or COPD (excess secretions accumulate in the lungs and through the effects of gravity gather in the lower zones of the lungs increases risk of infection)

26
Q

What is obstructive pneumonia?

A

Obstruction of a single bronchus

27
Q

What happens in bronchopneumonia?

A

The infection establishes in the small areas the bronchi, the small bronchi, and the bronchioles, and then spills over into the adjacent alveoli where we see pus,
neutrophil polymorphs and inflammatory exudates fill the airspaces.

28
Q

What are the outcomes/complications of pneumonia?

A
  • Most of them resolve with our without treatment (if not, why not?)
  • Pleurisy, pleural effusion, empyema
  • Organisation
  • Abscess
  • Bronchiectasis
  • Pneumonia is a potentially fatal disease
29
Q

What is empyema?

A

Pus accumulation

30
Q

What is organisation in an infection?

A

Instead of going away the infection turns to fibrous tissue and forms a mass lesion, small foci of infection and fibrosis which lead to obstruction of small airways.

31
Q

What are lung abscess?

A

They occur in the lung in different circumstances:

  • obstruction of a bronchus
  • Aspiration (food)
  • deposition of infection in the blood
  • when necrotic lung tissue becomes seondarily infected
32
Q

What organisms lead to lung abscess?

A

Staph aureus, some pneumonococci, Klebsiella

33
Q

What is bronchieactasis 1?

A

Pathological dilatation of bronchi to a size that is inappropriate for the position of
the bronchus in the bronchial tree.

34
Q

What is the pathological dilatation in bronchiectasis due to?

A
  • Severe infections
  • Recurrent infections
  • Proximal obstruction
  • surrounding lung tissue being destroyed
35
Q

What does bronchiectasis pose a risk of?

A

Severe bronchial hemmorhage

36
Q

What does recurrent lung infection imply?

A

That defence mechanisms of the lungs are failing.

37
Q

How are the defences of the lungs failing during recurrent lung disease?

A
  • Local bronchial obstruction - Tumour or foreign body
  • Local pulmonary damage - Bronchiectasis-
  • Generalised lung disease - Cystic fibrosis, COPD
  • Non respiratory disease - Immunocompromised, Aspiration
38
Q

What are the risk factors of aspiration pneumonia?

A

Vomiting, oesophageal lesion, obstetric anaesthesia, neuromuscular disorders, sedation

39
Q

What is normally sterile?

A

Lower respiratory tract

40
Q

How are particles cleared via the MMEs?

A
  • Foreign bodies are phagocytised by macrophages.
  • Macrophages migrate towards the cilia.
  • The cilia beat up and outwards
  • Digestions of foreign bodies get trapped in the mucous which is swept up the respiratory tract by the cilia and coughed out or swallowed.
  • Alternatively macrophages take the interstitial pathway via the lymph to the lymph nodes
41
Q

What happens if the MMEs fail?

A

Anything inhaled is retained in the lung.

42
Q

What can cause MMES to fail?

A

Viral infections as it can lad to the loss of cilia

43
Q

What are the symptoms of bronchiectasis?

A
  • Cough
  • Abundant purulent foul sputum
  • Haemoptysis
  • Signs of chronic infection
  • Coarse crackles
  • Clubbing
44
Q

How is bronchiectasis diagnosed?

A

Thin section CT

45
Q

How is bronchiectasis treated?

A

Postural drainage, antibiotics, surgery

46
Q

What are examples of opportunistic pathogens?

A
  • Low grade bacterial pathogens
  • CMV
  • Pneumocystitis jirovecii
  • Other fungi and yeasts