Acute Respiratory Infections

Question 1

What are the primary challenges the respiratory system faces from inspired air?

Answer 1

Inspired air introduces particles, toxic gases, and microorganisms.

Question 2

What is the largest epithelial surface exposed to the environment?

Answer 2

The airways.

Question 3

Why must the respiratory system eliminate foreign substances without excess inflammation?

Answer 3

To prevent tissue damage and preserve function.

Question 4

What can impairments in lung defence lead to?

Answer 4

Acute respiratory tract infections and other respiratory conditions.

Question 5

Name the three main lung defence mechanisms.

Answer 5

Physical/anatomical barriers, mechanical mechanisms, and immune-mediated responses.

Question 6

What physical features filter particles >10 µm in size?

Answer 6

Nasal hairs.

Question 7

What is the function of nasal turbinates?

Answer 7

Act as baffles to trap particles and promote removal by sneezing, coughing, or swallowing.

Question 8

What forms a physical barrier to pathogen entry in the respiratory tract?

Answer 8

Tight junctions between epithelial cells.

Question 9

What three components make up the mucociliary escalator?

Answer 9

Cilia, mucus, and airway surface liquid (ASL).

Question 10

How many cilia does each ciliated cell approximately have?

Answer 10

200–300.

Question 11

What size particles does tracheobronchial mucus trap?

Answer 11

2–10 µm.

Question 12

What happens after particles are trapped in mucus?

Answer 12

They are moved by cilia to the oropharynx to be swallowed or expectorated.

Question 13

What are PRRs and what do they detect?

Answer 13

Pattern recognition receptors detect PAMPs and DAMPs.

Question 14

What cells have PRRs like TLRs?

Answer 14

Antigen-presenting cells such as dendritic cells.

Question 15

What do chemokines and cytokines released by innate immune cells do?

Answer 15

Recruit and activate immune effector cells.

Question 16

What is the role of alveolar macrophages?

Answer 16

First-line phagocytic defence in alveoli.

Question 17

What is the function of alpha-one antitrypsin (A1AT)?

Answer 17

Inhibits proteases to prevent lung tissue damage.

Question 18

What antibody is predominant in upper airways?

Answer 18

Secretory IgA.

Question 19

What type of immunity is responsible for fighting intracellular pathogens?

Answer 19

Cell-mediated immunity (T lymphocytes).

Question 20

What is the role of BALT?

Answer 20

Bronchus-associated lymphoid tissue processes inhaled antigens for adaptive response.

Question 21

Define commensalism.

Answer 21

A relationship where one organism benefits and the other is unaffected.

Question 22

What is the difference between colonization and infection?

Answer 22

Colonization does not cause harm; infection involves tissue damage and inflammation.

Question 23

Give examples of respiratory tract commensals.

Answer 23

Viridans streptococci, H. influenzae, S. pneumoniae.

Question 24

What are common opportunistic pathogens of the URT?

Answer 24

S. pneumoniae, H. influenzae, M. catarrhalis, S. aureus.

Question 25

What affects the risk of respiratory infections?

Answer 25

Composition of the URT microbiome.

Question 26

Is the lower respiratory tract normally sterile?

Answer 26

Yes, in the absence of chronic disease.

Question 27

Name common URTIs.

Answer 27

Tonsillitis, pharyngitis, sinusitis, otitis media, laryngitis, common cold.

Question 28

What is the most common cause of URTIs?

Answer 28

Viruses.

Question 29

What are typical URTI symptoms?

Answer 29

Sore throat, nasal congestion, runny nose, sneezing, cough, headache, fever.

Question 30

Which anatomical regions are affected in LRTIs?

Answer 30

Trachea, bronchi, bronchioles, and lungs.

Question 31

Name examples of LRTIs.

Answer 31

Bronchitis, bronchiolitis, pneumonia.

Question 32

What is the leading cause of death among infectious diseases?

Answer 32

Lower respiratory tract infections.

Question 33

Name key bacterial pathogens in LRTIs.

Answer 33

S. pneumoniae, H. influenzae, S. aureus, Klebsiella spp, Legionella, Mycoplasma.

Question 34

Name important viral respiratory pathogens.

Answer 34

Influenza A/B, RSV, SARS-CoV-2, adenovirus.

Question 35

Name fungal pathogens.

Answer 35

Aspergillus, Pneumocystis jirovecii.

Question 36

What defines acute bronchitis?

Answer 36

Inflammation of the tracheo-bronchial tree with cough and no consolidation.

Question 37

What are typical causes of acute bronchitis?

Answer 37

Viruses (most common), H. influenzae, S. pneumoniae.

Question 38

What indicates infective COPD exacerbation?

Answer 38

Increased sputum volume or purulence.

Question 39

What is pneumonia?

Answer 39

LRTI with radiographic consolidation and clinical signs/symptoms.

Question 40

Name pneumonia types based on radiological pattern.

Answer 40

Lobar, bronchopneumonia, interstitial, cavitating.

Question 41

What causes lobar pneumonia most commonly?

Answer 41

Streptococcus pneumoniae.

Question 42

What organisms cause cavitating pneumonia?

Answer 42

S. aureus, Klebsiella, Mycobacterium tuberculosis.

Question 43

Who is at greater risk for CAP?

Answer 43

Elderly, males, and people with comorbidities like COPD.

Question 44

What are classical symptoms of CAP?

Answer 44

Fever, chills, cough, pleuritic chest pain.

Question 45

What score is used to assess CAP severity?

Answer 45

CURB-65.

Question 46

What does a CURB-65 score of 4–5 indicate?

Answer 46

High risk – consider ICU admission.

Question 47

How is Legionella transmitted?

Answer 47

Inhalation of contaminated aerosols.

Question 48

What is the treatment for Legionella pneumonia?

Answer 48

Macrolides or quinolones (not penicillin).

Question 49

What is a characteristic finding in Mycoplasma pneumonia?

Answer 49

Extensive CXR changes with mild clinical symptoms ("walking pneumonia").

Question 50

What is essential before antibiotic therapy in pneumonia?

Answer 50

Collect respiratory samples and blood cultures.

Question 51

What test detects Legionella infection?

Answer 51

Urine antigen test.

Question 52

How is Mycoplasma diagnosed?

Answer 52

Molecular testing of upper respiratory swabs.

Question 53

When does Hospital Acquired Pneumonia typically occur?

Answer 53

>48 hours after hospital admission or post-discharge

Question 54

What are late HAP pathogens?

Answer 54

Pseudomonas, E. coli, Klebsiella, MRSA, anaerobes.

Question 55

What vaccines help prevent respiratory infections?

Answer 55

HiB, pneumococcal, pertussis, influenza, COVID vaccines.

Question 56

What lifestyle intervention reduces pneumonia risk?

Answer 56

Smoking cessation.