Respiratory tract infections

Question 1

Cause of the common cold

Answer 1

Normally viral: rhinovirus, coronavirus, RSV,adenovirus

Question 2

Mechanisms which normally protect the lungs from infection

Answer 2

Upper airway reflexes e.g. cough

Mucociliary escalator. Consists of a glycoprotein matrix which traps particles, lysozyme to digest peptidoglycan and lactoferrin to bind Fe and LPS.

Defensins and IgA in mucus

Cells: Phagocytes, NK cells, mast cells

Question 3

Define pneumonia

Answer 3

Infection of the alveolar space and/or interstitial parenchyma

Pneumonitis is inflammatory disease that is non-infective

Question 4

Clinical presentation of pneumococcal pneumonia

Answer 4

Abrupt onset rigors, high fever, cough, dyspnoea, pleuretic chest pain

rust coloured sputum

Complications of infection: lung abscess, parapneumonic effusion, empyema

Question 5

Clinical presentation of mycoplasa pneumonia

Answer 5

Fever, mailaise, non-productive cough, headache

No peptidoglycan, detected by serology or PCR

Question 6

What features may indicate legionella infection in a patient presenting with cough, dyspnoea, fever and chest pain?

Answer 6

Signs indicate pneumonia

History of travel/ air conditioning

Diagnosis with serology or presence of antigen in the urine

Question 7

Biomarkers used in LRTI

Answer 7

CRP

Pro-calcitonin

Both raised in inflammation

Question 8

How can you improve prognosis in a patient with pneumonia

Answer 8

Administration of antibiotics within 4hrs of presentation

Question 9

How do you distinguish between pneumonia and exacerbation of COPD

Answer 9

Pneumonia tends to be bacterial

Exacerbations of COPD are mainly viral. Do not show X-ray changes seen in pneumonia e.g. consolidation, effusion.

Treat exacerbation of COPD with antibiotics if there is purulent sputum.

Question 10

Nosocomial pneumonia

Answer 10

Pneumonia acquired after 48hrs hospital admission.

Tends to be G -ve e.g. Klebsiella, pseudomonal, e.coli) or S. aureus.

Question 11

Bronchiectasis

Answer 11

Abnormal permanent dilation of bronchi

Causes: Cystic fibrosis, connective tissue disorders, immune defects

Question 12

Diagnosis of cystic fibrosis

Answer 12

Sweat test

Sputum examination and culture

Blood analysis for gene defect

Question 13

Cause of cystic fibrosis

Answer 13

Autosomal recessive disease

Mutation causes deletion in CFTR protein which is a Cl- channel.

Mutation alters structure of protein so channel fails to open. Decreased Cl- excretion increases reabsorption of Na+ and H2O into cells. Viscosity of secretions is increased - particulatly in the airway and pancreas.

Question 14

Advantages and disadvantages of inhaled antibiotics

Answer 14

Adv: Low absorption outside the lungs, fewer side effects, easier monitoring Disadv: resistance, high costs with long term use, time consuming

Question 15

Causes of sore thorat

Answer 15

EBV
Adenovirus S. pyogenes C. diptheriae

Question 16

Sinusitis

Answer 16

Periodic facial pain made worse on leaning forwards

Question 17

Difference between broncho and lobar pneumonia

Answer 17

Bronchopneumonia is diffuse and patchy

Lobar pneumonia localised to a particular lobe of the lung.

Question 18

Aspiration pneumonia

Answer 18

Caused by aspiration of food, drink, saliva or vomit into the lungs. More likely in patients who are unconscious, congenital/anatomical abnormalities or drug/alcohol abuse.