Lung Infection

Question 1

What is an example of the local barrier of the respiratory tract against infection?

Answer 1

Bronchus associated lymphoid tissue

Question 2

Describe the two layers of fluid surrounding and above the cilia.

Answer 2

Watery periciliary fluid

Mucus (thick and gel-like)

Question 3

What structures knit the epithelia into a cohesive layer?

Answer 3

Tight junctions

Question 4

How fast does each cilium beat?

Answer 4

15 times per second

Question 5

Describe how the cilium is withdrawn after the forward stroke.

Answer 5

It is withdrawn in a curved fashion within the periciliary fluid and under the mucus so that it doesn’t pull the mucus back in the opposite direction.

Question 6

Describe the rhythm of the cilia.

Answer 6

Metachronal rhythm

Question 7

Describe the ultrastructure of the cilium.

Answer 7

It has a 9+2 structure - it has 9 microtubule pairs around the outside and two microtubules in the middle
The outer microtubule pairs have inner and outer dynein arms

Question 8

What enables the cilia to move?

Answer 8

ATPase on the dynein arms

Question 9

If a patient has recurrent chest infections, where could the problem be?

Answer 9

It could be a bad infection itself

But it could also be a problem with the host defence

Question 10

Give two examples of acquired defects of the mucociliary system.

Answer 10

Smoking

Viral infections

Question 11

Why do bacterial infections often follow viral infections?

Answer 11

Viruses can damage the epithelia allowing the bacteria to dock down and colonise

Question 12

What can happen to the cilia when they grow back?

Answer 12

They can regrow abnormally and form compound cilia, which are useless

Question 13

What is the relationship between cilia and dextrocardia?

Answer 13

50% of people born without functioning cilia have dextrocardia
This is because the microtubules are involved in guiding cells around during embryological development.

Question 14

What is the term given for congenital disease causing malfunctioning cilia? How does this disease affect the ultrastructure of the cilium?

Answer 14

Primary ciliary dyskinesia - this is caused by a dynein arm defect

Question 15

What biochemical marker is used to assess risk of primary ciliary dyskinesia before performing nasal biopsy?

Answer 15

People with primary ciliary dyskinesia have lower levels of nasal nitric oxide than people without.

Question 16

What is the most common cause of bronchitis and sinusitis?

Answer 16

Haemophilus influenza

Question 17

What parts of the epithelium does bacteria stick to?

Answer 17

Damaged areas of epithelium - they do not stick to the ciliated epithelium

Question 18

Examples of community acquired bacteria and hospital acquired bacteria

Answer 18

Community = Strep pneumoniae, Mycoplasma pneumoniae, Staph aureus,
Chlamydophila pneumoniae, Haemophilus influenzae

Hospital = Staph aureus (28%), Pseudomonas aeruginosa, Klebsiella species, E. coli, Acinetobacter species, Enterobacter species

Question 19

How to investigate pneumonia?

Answer 19

Chest radiograph, blood tests (including C reactive protein), ABG, microbiological investigations.

Question 20

Guidelines for diagnosing pneumonia

Answer 20

Acute lower respiratory tract symptoms.
NEW focal chest signs and NEW chest X-ray changes in hospital.
More than 1 systemic feature.
No other explanation for illness.

*In acute bronchitis, there is coughing but only tracheal pain - not pleuritic, and there are no new X-ray changes.

Question 21

Treatment for pneumonia?

Answer 21

Supportive therapy: oxygen for hypoxia, fluids for dehydration, analgesia for pain, nebulised saline.

Antibiotic therapy: should be as quick as possible, duration is typically 1 week.