Suppurative lung diseases

Question 1

What are the similarities between all suppurative lung conditions? (8)

Answer 1

All suppurative ie pus forming
* All essentially complications of lung infections
* All due to bacteria including some unusual ones
* All chronic problems
* All require antibiotics often for prolonged periods
* Therefore, important to try to get representative samples for culture and susceptibility testing
before starting treatment
* Often require physiotherapy to encourage drainage of excess or thick sputum (bronchiectasis
and lung abscess)
* May require surgery to drain pus (lung abscess and empyema)

Question 2

What is the morphology of bronchiectasis?

Answer 2

Abnormal bronchi and bronchioles - permanently dilated

Question 3

What is the pathogenesis of bronchiectasis?

Answer 3

due to previous inflammation in surrounding lung tissue  resultant scarring or fibrosis
causes dilatation of bronchi. Then ongoing inflammatory changes lead to further damage to airways

Question 4

What are the symptoms of bronchiectasis?

Answer 4

Chronic cough with copious amounts of sputum production

Question 5

What are the complications of bronchiectasis?

Answer 5

-Recurrent pneumonia and lung abscess
* Distant spread via blood stream causing abscesses in remote parts of body ‘metastatic abscess’ e.g. brain
* Pulmonary fibrosis
* Cor pulmonale ( right heart failure secondary to lung disease)
* Amyloidosis

Question 6

Which infections can lead to the development of bronchiectasis?

Answer 6

Severe infections such as TB, measles, pertussis, adenovirus
2. Underlying genetic abnormalities that predispose to severe infections: cystic fibrosis with abnormally thick
secretions that can’t be cleared, immotile cilia, hypogammaglobulinaemia, others

Question 7

Which genetic condition can predispose to severe infection

Answer 7

cystic fibrosis with abnormally thick secretions that can’t be cleared, immotile cilia, hypogammaglobulinaemia, others

Question 8

Which microbe is associated with bronchiectasis?

Answer 8

Pseudomonas aeruginosa

Question 9

What type of bacteria is Pseudomonas aeruginosa?

Answer 9

Gram negative bacilli

Question 10

Can Pseudomonas aeruginosa infect healthy tissues under normal circumstances?

Answer 10

No, it is an opportunistic pathogen that rarely infects healthy tissues.
If defenses are compromised, it can infect virtually all
tissues in the body leading to a wide variety of infections

Question 11

How does Pseudomonas aeruginosa affect patients with bronchiectasis and chronic lung damage?

Answer 11

Can cause pneumonia in patients with bronchiectasis
and chronic lung damage

Question 12

Whar is another term for lung abscess?

Answer 12

Necrotising pneumonia

Question 13

What happens in lung abscess/necrotising pneumonia?

Answer 13

There is a focal breakdown of lung tissue

Question 14

What are the symptoms of lung abscess?

Answer 14

Lots of sputum, often smelling bad due to anaerobes

Question 15

How is a lung abscess diagnosed?

Answer 15

CXR: air-fluid level classic finding

Question 16

Explain different ways in which a lung abscess can develop. (4)

Answer 16

1. As a result of severe lung infection - S. aureus is notorious for causing breakdown of lung tissue
2. As a consequence of a blockage of a local area of lung (e.g by a tumor or foreign body) leading to unresolving infection.
3. Occasionally from haematogenous/blood borne spread
4. Most commonly as a complication of aspiration pneumonia ( Aspiration of fluid or food into lung causing inflammation, sometimes termed ‘macro
   aspiration’)

Question 17

Which patients are at risk of developing aspiration pneumonia?

Answer 17

Patients at risk : sedated or with reduced level of consciousness or swallowing problems

Question 18

Which organisms cause lung abscess?

Answer 18

Anaerobes
S. aureus
Typical respiratory bacteria
-Often polymicrobial – more than one microorganism present

Question 19

How do anaerobes cause lung abscess? How do they end up in the lung?

Answer 19

Anaerobes are commonly associated with aspiration pneumonia- come from the mouth. They enter the lung through aspiration

Question 20

How does S. aureus cause lung abscess? How does it end up in the lung?

Answer 20

-Staphylococcus aureus can be acquired via respiratory tract, especially after preceding viral
infection
* Can also be result of haematogenous spread when there can be multiple
lung abscesses

Question 21

What is Haemothorax? what causes it?

Answer 21

It is a collection of blood in the pleural cavity, caused by trauma or raptured aortic aneurysm

Question 22

What is transudate hydrothorax? What causes it?

Answer 22

It is a collection of low protein fluid in the pleural cavity. Caused by Liver failure; cardiac failure; renal failure

Question 23

What is exudate hydrothorax? What causes it?

Answer 23

It is a collection of low protein fluid in the pleural cavity. Caused by Tumours; infection; inflammation

Question 24

What is Chylothorax? what causes it?

Answer 24

Collection of lymph in the pleural cavity, caused by Neoplastic obstruction of thoracic lymphatics

Question 25

What is a pneumothorax, what causes it?

Answer 25

It is a collection of air in the pleural cavity. It can be Spontaneous, following rupture of alveolus or bulla in emphysema or tuberculosis. Or it can be traumatic, e.g. following penetrating
injuries of the chest

Question 26

What is pyothorax? what causes it?

Answer 26

It is a collection of pus in the pleural cavity. Caused by infection.

Question 27

What is pleural effusion? What is its common cause?

Answer 27

Pleural effusion:
* fluid in pleural space
* Common in bacterial pneumonia if infection involves pleura
* Often fairly small and resolve spontaneously

Question 28

What is pleural empyema? What causes it?

Answer 28

Pleural empyema:
* Pus in pleural space
* Occurs if pleural effusion becomes more purulent, e.g. S. aureus infection can cause pus
* Or if get secondary infection of other fluid, e.g. Infected haemothorax

Question 29

How is pleural empyema treated?

Answer 29

Need some form of drainage to remove pus plus antibiotics

Question 30

What happens if the pleural empyema is left untreated?

Answer 30

Untreated - ongoing infection, lung unable to expand and gets stuck down permanently by
scar tissue/fibrosis.