L22. Pathology of Lung Infection (Pneumonia) Flashcards Preview

03. Respiratory > L22. Pathology of Lung Infection (Pneumonia) > Flashcards

Flashcards in L22. Pathology of Lung Infection (Pneumonia) Deck (64):
1

What is pneumonia?

Inflammation of the lung parenchyma (lower respiratory lung inflammation) which is most often due to infectious means

2

What is acute inflammation? What are the three key events?

A vascular reaction to some form of injury
1. Dilation
2. Increased vascular permeability
3. Infiltration

3

What is acute inflammation? What are the three key events?

A vascular reaction to some form of injury
1. Dilation
2. Increased vascular permeability
3. Infiltration

4

What are the major symptoms of pneumonia?

Shortness of breath
Pleuritic chest pain (depending on the type of pneumonia)
Often purulent sputum
If infective: then there is often fever

5

What are the major symptoms of pneumonia?

Shortness of breath
Pleuritic chest pain (depending on the type of pneumonia)
Often purulent sputum
If infective: then there is often fever

6

What are the causative organisms and the characteristics of the 'classic' pattern of acute inflammation in the lung?

The traditional bacteria (typical)
- aerobic and easy to grow
- S. pneumonia, Klebsiella, P. aeruoginosa, Legionella

7

What are some atypical organisms that cause an atypical pattern of acute inflammation?

Mycoplasma and some viruses

8

What are the two patterns of acute bacterial pneumonia?

Acute Bronchopneumonia
Acute Lobar pneumonia

9

Which pattern of acute pneumonia is most common? Why?

Bronchopneumonia is far more common (causative organisms of the lobar pneumonia have been less effective in the antibiotic era)

10

Which pattern of acute pneumonia is most common? Why?

Bronchopneumonia is far more common (causative organisms of the lobar pneumonia have been less effective in the antibiotic era)

11

What is the difference between community acquired pathogens and hospital acquired?

Community acquired tend to be gram positives and normal flora and more susceptible to antibiotics

Hospital acquired tend to be gram negative and resistant to antimicrobials because they are equipped to replicating under the stress of high antibiotic use environments

12

How is aspiration a cause of pneumonia?

Aspiration of gut contents and secretions and of upper respiratory tract secretions into the throat and into the respiratory tract can occur and cause pneumonia.
- a normal physiological process but more often and problematic for people with altered conscious levels
- important because anaerobic bacteria may be the cause

13

What is the most important defence against lung infection (especially pnuemonia)?

A fully functional immune system

14

What are some other compromised lung defense mechanisms? [5]

- loss of a cough reflex ( anaesthesia, NM diseases, etc)
- impairment of mucocilary action
- Accumulation of secretions (CF, bronchial obstruction)
- Interference with phagocytic or bactericidal actoin of alveolar macrophages (alcohol, smoking)
- Pulmonary congestion and oedema

15

What are some other compromised lung defense mechanisms? [5]

- loss of a cough reflex ( anaesthesia, NM diseases, etc)
- impairment of mucocilary action
- Accumulation of secretions (CF, bronchial obstruction)
- Interference with phagocytic or bactericidal actoin of alveolar macrophages (alcohol, smoking)
- Pulmonary congestion and oedema

16

What are some predisposing factors to bacterial pneumonia?

Smoking
Reduced cough
Debility and malnutrition
Bronchial obstruction
Immune Suppression
Hospitalisation
Surgery/anesthesia
Alcoholism
Viral infections (leads to secondary infections)

17

What are some predisposing factors to bacterial pneumonia?

Smoking
Reduced cough
Debility and malnutrition
Bronchial obstruction
Immune Suppression
Hospitalisation
Surgery/anesthesia
Alcoholism
Viral infections (leads to secondary infections)

18

What determines what type of acute bacterial pneumonia is labelled what? (lobar vs. bronco)

The distribution of inflammation

19

What determines what type of acute bacterial pneumonia is labelled what? (lobar vs. bronco)

The distribution of inflammation

20

What is the localisation of inflammation of lobar pneumonia? What does this imply about the organism?

Affects the entirety of the lob with NO area spared
- implies the pathogen is highly virulent and the inflammation and oedema is thus spread very rapidly through the whole lobe

21

What are the most common causes of lobar pneumonia?

Streptococcus pneumonia followed by Haemophilus influenzae

22

What are the most common causes of lobar pneumonia?

Streptococcus pneumonia followed by Haemophilus influenzae

23

What are the distinguishing features/symptoms of lobar pneumonia?

The patient is more likely to experience pleuritis (as the inflammation spreads to the pleura) and you hear 'bronchial breath sounds' over the area

24

What is the localisation of inflammation of lobar pneumonia? What does this imply about the organism?

Affects the entirety of the lob with NO area spared

- implies the pathogen is highly virulent and the inflammation and oedema is thus spread very rapidly through the whole lobe

25

What are the distinguishing features/symptoms of lobar pneumonia?

The patient is more likely to experience pleuritis (as the inflammation spreads to the pleura) and you hear 'bronchial breath sounds' over the area

26

What is the localisation of inflammation of bronchopneumonia? What does this imply about the organism?

A PATCHY distribution of inflammation: multiple discrete foci separated by areas of normal, uninflammed lung

- implies the pathogen is not highly virulent
- suggests that the inflammation starts at the terminal bronchioles and spreads out to the alveolar parenchyma

27

Does bronchopneumonia only involve one lobe?

No it often involves multiple lobes and is often bilateral

28

Does bronchopneumonia only involve one lobe?

No it often involves multiple lobes and is often bilateral

29

Is there always a large distinction between the two types of acute bacterial pneumonia?

No
There is often a large overlap between their presentations and the type is often not relevant to clinical practice

30

Is there always a large distinction between the two types of acute bacterial pneumonia?

No
There is often a large overlap between their presentations and the type is often not relevant to clinical practice

31

Acute bacterial pneumonias cause the classical pathologic change of consolidation. Define consolidation

Where normal aerated lung tissue is filled with fluid or inflammatory cells making it non-compressible, firm to touch and more solid

32

Acute bacterial pneumonias cause the classical pathologic change of consolidation. Define consolidation

Where normal aerated lung tissue is filled with fluid or inflammatory cells making it non-compressible, firm to touch and more solid

33

What does consolidation look like macroscopically?

Pale and solid

34

What are the histological features of consolidation for acute bronchopneumonia?

Inflammatory cells in the septa
Inflammatory cells and exudate (pus) in the alveolar spaces and in the airways
Increased blood flow - dilated vessels

35

What are the histological features of consolidation for acute bronchopneumonia?

Inflammatory cells in the septa
Inflammatory cells and exudate (pus) in the alveolar spaces and in the airways
Increased blood flow - dilated vessels

36

What are the two morphological classifications of consolidation in acute lobar pneumonia?

Red hepatisation: lung looks red and solid representing an earlier stage of pneumonia due to large amounts of haemorrhage

Grey Hepatisation: later stages when polymorph (neutrophil) infiltrates take over the cellular population and the lung begins to look pale grey and solid

37

What is a lung abscess?

A collection of pus in the lungs

38

What are some causes of lung abcsess?

Aspiration (a common cause)
Obstruction of the bronchial tree
Haemotgenous seeding from an extra-pulmonary infection
Some types of bacterial pneumonias (S. pyogenes, K.pneumonia, S.aureus) - especially in debilitated hosts
Aspiration of foreign bodies
Trauma (accidental or surgical)

39

What are some causes of lung abcsess?

Aspiration (a common cause)
Obstruction of the bronchial tree
Haematogenous seeding from an extra-pulmonary infection
Some types of bacterial pneumonias (S. pyogenes, K.pneumonia, S.aureus) - especially in debilitated hosts
Aspiration of foreign bodies
Trauma (accidental or surgical)

40

What are some causes of lung abcsess?

Aspiration (a common cause)
Obstruction of the bronchial tree
Haematogenous seeding from an extra-pulmonary infection
Some types of bacterial pneumonias (S. pyogenes, K.pneumonia, S.aureus) - especially in debilitated hosts
Aspiration of foreign bodies
Trauma (accidental or surgical)

41

What are the features of viral pneumonia?

- No consolidation (do get oedema and extravasation of fluid)
- Lymphocyte dominated
- Can cause bronchiolitis and inflammation of the septa (not the alveoli)
- Predisposes to secondary bacterial infections

42

What are the features of viral pneumonia?

- No consolidation (do get oedema and extravasation of fluid)
- Lymphocyte dominated
- Can cause bronchiolitis and inflammation of the septa (not the alveoli)
- Predisposes to secondary bacterial infections

43

What is a major example of a virus that causes bronchiolitis?

Respiratory Syncytial Virus that causes infiltration of lymphocytes to the bronchial wall

44

What are the two major chronic infections affecting the lower respiratory tract?

Bronchiectasis and pulmonary TB

45

What is bronchiectasis?

The irreversible dilation of the large, cartilaginous containing airways (bronchi)

46

What is the cause of the dilatation in bronchiectasis?

Scar tissue deposition around the bronchi and weakening of the bronchial wall by inflammation - mainly by a CHRONIC BACTERIAL INFECTION and this contributes to the pooling of secretions that cannot be cleared (exacerbates chronicity of infection)

47

What is the cause of the dilatation in bronchiectasis?

Scar tissue deposition around the bronchi and weakening of the bronchial wall by inflammation - mainly by a CHRONIC BACTERIAL INFECTION and this contributes to the pooling of secretions that cannot be cleared (exacerbates chronicity of infection)

48

What is an important predisposition to bronchiectasis?

Airway obstruction

49

What is a very serious sequelae of bronchiectasis?

Cyst frmation

50

Where are bronchi normally distributed? How is this different in bronchiectasis?

Normally bronchi (as cartilage containing airways) are at the centre of the lungs and reduce in number to the periphery.
In bronchiectasis, the bronchi become so prominent and dilated they appear at the periphery

51

Where are bronchi normally distributed? How is this different in bronchiectasis?

Normally bronchi (as cartilage containing airways) are at the centre of the lungs and reduce in number to the periphery.
In bronchiectasis, the bronchi become so prominent and dilated they appear at the periphery

52

What are some complications of bronchiectasis?

Copious offensive sputum
Poor drainage of secretions = recurrent bacterial pneumonia and abscess formation
Rupture of vessels in bronchial walls = haemoptysis
Pulmonary fibrosis leading to RV failure (cor pulmonale)
Cerebral abcessess
Amyloidosis

53

What is TB caused by? Give characteristics of the organsim

Acid fast mycobacterium TB that is spread by droplets, is aerobic

54

What are the two main characteristics of TB infection?

1. Granulomatous inflammation: granulomas (type 4 sensitivity reaction) to wall of the infection which is impossible for the body to clear

2. Caseous necrosis: at the centre of the granulomas that destroys the tissue and parencyma

55

What is a tubercle?

A basic inflammatory lesion characteristic to TB - an area of granulomatous inflammation and casesous necrosis and is often about 2 cm.

As the disease progresses they can grow larger and even fuse

56

What is primary TB?

Patten of TB that occurs upon first exposure to the bacterium. If most often occurs in young children and can be unsymptomatic and undetected

57

What are clinical presentations of primary TB?

A mild, self limiting illness that is often subclinical

58

Are there ares of granulomatous inflammation in primary TB? Explain

Granulomatous inflammation occurs at the PERIPHERY (usually in the midzone) with caseous necrosis = GHON FOCUS

Drainage of the bacteria into the hilar lymph nodes causes them to caseate (white nodular appearances)

Ghon Focus + Involved Node = GHON COMPLEX

59

What happens to these ghon complexes in an immune healthy host?

Ghon complexes are controlled and completely heal off by fibrosis (often with some calcification)

60

What is secondary TB? What causes it? [2]

Occurs in patients that have previously been infected with the bacterium and thus have a fully sensitised response to it.
1. Reactivation of the infection (usually decades later and due to some immunocompromisatin)
2. Reinfection

61

What is the pathology of secondary TB?

Areas of granulomatous inflammation appear in the upper lobes = APICAL areas
The extend of the tubercles and caseation is much more severe causing more damage

CAVITATION occurs of the caseous necrosis where it erodes into the wall of the bronchus and discharges into the bronchial tree

Dystrophic calcification

62

What keeps the caseation limited?

walling off by fibrosis (scar formation) which is damaging to the lung tissue (decreases compliance)

63

What are some complications of secondary pulmonary TB?

Progressive spread of caeseation into surrounding lung
Erosion of blood vessels (haemoptysis)
Erosion into bronchial tree (cavitation and spread)
Pleural inflammation and fibrosis
Lung scarring

64

What is miliary TB?

Numerous small granulomas widely scattered in the lungs or other organs caused by dissemination of the TB via blood vessels (haemoatogenous spread) - small seed like
- high mortality
- both primary and secondary TB
- can effect any organs