Lobar pneumonia - CAP

Question 1

What happens to the lungs in CAP?

Answer 1

You get inflammation of the lungs with consolidation or interstitial lung infiltrates.

Question 2

What does CURB-65 stand for?

Answer 2

· Confusion - 1pt. 
· Urea >7mmol/L - 1pt.
· RR >30 - 1pt. 
· BP systolic <90 or diastolic <60 - 1pt. 
· Age >65yrs - 1pt.

Question 3

What is the epidemiology?

Answer 3

· LRTI are the most deadly infectious disease.
· Incidence increases with age.
· More common in men.

Question 4

What is the pathophysiology of CAP?

Answer 4

· Invasion and overgrowth of a pathogenic microorganism in the lung parenchyma.
· It overwhelms host defences and produces intra-alveolar exudates.
· The defence mechanisms of the lungs should keep the lower airways sterile.
· The development of pneumonia indicates a defect in host defences, exposure to a virulent organism or large inoculum size.

Question 5

Pathogens can reach the lower respiratory tract by which 4 mechanisms?

Answer 5

1. Inhalation.
2. Aspiration of oropharyngeal secretions.
3. Haematogenous spread from a localised infection site.
4. Direct extension from adjacent infected foci.

Question 6

Prognosis is determined by which 3 factors?

Answer 6

1. Age.
2. Comorbidities.
3. Setting where abx treatment is given.

Question 7

What is the aetiology of CAP?

Answer 7

· Strep pneumoniae - most common causative pathogen.
· Haemophilus influenzae.
· Staph aureus.
· Group A strep.
· Atypical bacteria - mycoplasma pneumoniae, legionella pneumoniae.
· Pseudomonas aeruginosa.
· Viruses - influenza, RSV.

Question 8

List the common risk factors associated with CAP.

Answer 8

· Age >65 years. 
· Residence in a healthcare setting. 
· COPD.
· Exposure to cigarette smoke. 
· Alcohol abuse. 
· Poor oral hygiene. 
· Use of acid-reducing drugs - PPI's. 
· Contact with children. 
· Diabetes.
· CKD.
· Chronic liver disease.

Question 9

List the common signs and symptoms associated with CAP.

Answer 9

· Cough with increasing sputum production. 
· Fever or chills. 
· Dyspnoea. 
· Pleuritic pain. 
· Abnormal auscultatory findings.
· Confusion - older patients.

Question 10

What abnormal auscultatory findings might you find?

Answer 10

· Asymmetric breath sounds.
· Pleural rubs.
· Increased fremitus.
· Dullness to percussion - consolidation or pleural effusion.

Question 11

What investigations would you do if you suspected a patient had CAP?

Answer 11

· CXR.
· FBC - leukocytosis. 
· U&Es, LFTs, CRP, procalcitonin. 
· Glucose. 
· ABG - may reveal low arterial oxygen saturation.
· Blood cultures.
· Sputum cultures. 
· Bronchoscopy.

Question 12

Differentials?

Answer 12

· Acute bronchitis - no dyspnoea, no crackles, often related to viral URTI.
· Congestive heart failure.
· Asthma/COPD/Bronchiectasis exacerbation.
· Lung cancer/mets.
· Empyema.

Question 13

What is the treatment for CAP?

Answer 13

· Abx prescription differs with comorbidities, drug resistance, outpatient/hospital.

· 1st line usually amoxicillin - If penicillin allergic give macrolide or tetracycline therapy, e.g. azithromycin.
· Co-morbidities - 1st line = fluoroquinolone.

· Supportive care.

• Outpatients - No smoking, rest, 1-2L fluid a day.
• Hospital - Oxygen, monitoring, fluids.

· Corticosteroids.

Question 14

What medium risk complications may occur?

Answer 14

· Septic shock - fever, leukocytosis, tachypnoea and tachycardia.
· ARDS - non-cardiogenic pulmonary oedema and severe lung inflammation.
· Abx-associated C diff colitis - diarrhoea, abdominal pain and leukocytosis.
· Heart failure.

Question 15

What low risk complications may occur?

Answer 15

· Acute coronary syndrome.
· Cardiac arrhythmias. 
· Necrotising pneumonia. 
· Pleural effusion.
· Lung abscess.