Why Pneumonia Is Examined
Community-acquired pneumonia (CAP) is the most common infectious cause of death in the UK, with over 220,000 hospital admissions per year. It is examined in OSCEs through acute management stations, prescribing (write the antibiotic prescription), data interpretation (CURB-65 scoring), and CXR interpretation. Examiners test CURB-65 application, correct antibiotic choice for severity, and safe discharge planning.
Presentation
Symptoms:
- Productive cough (purulent sputum)
- Fever, rigors
- Pleuritic chest pain
- Dyspnoea
- Confusion (especially in elderly — may be the only feature)
Signs:
- Fever (above 38 degrees C)
- Tachycardia, tachypnoea
- Dullness to percussion (consolidation)
- Bronchial breathing + vocal resonance/tactile fremitus increased over consolidation
- Reduced air entry
- Coarse crackles (may clear with cough)
Investigations
| Investigation | Findings |
|---|---|
| CXR | Lobar or patchy consolidation, pleural effusion (parapneumonic), air bronchograms |
| FBC | Raised WCC (neutrophilia in bacterial; lymphocytosis in viral/atypical) |
| CRP | Raised (correlates with severity; useful marker of response to treatment) |
| U&E | Urea (used in CURB-65); hyponatraemia in Legionella and SIADH |
| Blood cultures | Take before antibiotics — positive in 10-15% of CAP |
| Sputum MC&S | If productive cough and not already on antibiotics |
| Urine Legionella antigen | For moderate-severe CAP (CURB-65 2 or above) |
| Urine pneumococcal antigen | For severe CAP |
| ABG | If SpO2 below 92% or respiratory failure suspected |
CURB-65 Severity Score
| Criterion | Points |
|---|---|
| C onfusion (new — AMT below 8 or new disorientation to time/place/person) | 1 |
| U rea above 7 mmol/L | 1 |
| R espiratory rate 30/min or above | 1 |
| B lood pressure: systolic below 90 OR diastolic 60 mmHg or below | 1 |
| 65 Age 65 years or above | 1 |
| Score | Severity | Management |
|---|---|---|
| 0-1 | Low (mortality below 3%) | Consider home treatment |
| 2 | Moderate (mortality 9%) | Hospital admission |
| 3 or above | High (mortality 15-40%) | Urgent hospital assessment; consider ITU if score 4-5 |
💡 Tip
CURB-65 guides admission, not antibiotic choice. A CURB-65 of 0-1 in a patient with comorbidities, bilateral pneumonia, hypoxia, or social concerns may still warrant admission. Clinical judgment overrides the score.
Empirical Antibiotic Treatment (BTS/PHE Guidelines)
Low Severity (CURB-65 0-1) — Community/Oral
| Drug | Dose | Duration |
|---|---|---|
| Amoxicillin | 500 mg TDS | 5 days |
| Doxycycline (if penicillin allergy or atypical suspected) | 200 mg loading then 100 mg OD | 5 days |
Moderate Severity (CURB-65 2) — Oral
| Drug | Dose | Duration |
|---|---|---|
| Amoxicillin | 500 mg TDS | 7 days |
| Plus clarithromycin (atypical cover) | 500 mg BD | 7 days |
High Severity (CURB-65 3 or above) — IV
| Drug | Dose | Duration |
|---|---|---|
| Co-amoxiclav | 1.2 g TDS IV | 7-10 days total (step down to oral when CRP halving, apyrexial, eating/drinking) |
| Plus clarithromycin | 500 mg BD IV/oral | 7-10 days |
Penicillin allergy (severe):
- Co-trimoxazole (trimethoprim-sulfamethoxazole) or levofloxacin (as per local guidance)
- Always check local antibiogram
Atypical Pneumonias
Atypical organisms do not respond to beta-lactam antibiotics (no cell wall target) — require macrolide, tetracycline, or fluoroquinolone.
| Organism | Clinical clues | Antibiotic |
|---|---|---|
| Mycoplasma pneumoniae | Young adults, epidemics every 4 years, "walking pneumonia", erythema multiforme, cold agglutinins, diarrhoea | Clarithromycin / doxycycline |
| Legionella pneumophila | Air conditioning, hotel/hospital outbreaks, hyponatraemia, raised LFTs, confusion, abdominal pain | Clarithromycin or levofloxacin |
| Chlamydophila pneumoniae | Atypical presentation, pharyngitis preceding | Clarithromycin |
| Chlamydophila psittaci | Bird exposure (parrots, pigeons) — occupation/hobby history | Doxycycline |
| Coxiella burnetii (Q fever) | Livestock exposure — farmers, abattoir workers | Doxycycline |
💎 Clinical Pearl
Always ask about occupational and exposure history in atypical pneumonia — a farmer with atypical pneumonia may have Q fever; a pet shop worker may have psittacosis. These require different antibiotics and are notifiable diseases.
Complications of Pneumonia
| Complication | Features | Management |
|---|---|---|
| Parapneumonic effusion | Pleural fluid on CXR; dullness, reduced breath sounds | Aspirate if significant; send for pH, glucose, LDH, MC&S |
| Empyema | Infected pleural fluid (pH below 7.2, glucose below 2.2, LDH above 1000) | Chest drain + IV antibiotics |
| Lung abscess | Cavitating lesion on CXR, foul sputum, prolonged course | Prolonged antibiotics (4-6 weeks); consider bronchoscopy |
| Respiratory failure | Hypoxaemia failing high-flow O2 | NIV/CPAP for type 2; HDU/ITU |
| Sepsis | Organ dysfunction (AKI, coagulopathy, altered consciousness) | Sepsis 6 bundle; IV antibiotics; escalate |
Discharge Criteria and Safety Netting
BTS "SMART" discharge criteria (all must be met):
- SpO2 above 94% on air (or at baseline for COPD)
- No more than 1 of CURB-65 criteria present
- Apyrexial for over 24 hours
- Eating and drinking
- Able to take oral medication
Before discharge:
- CXR reported (if not done — arrange 6-week repeat CXR to confirm resolution)
- Oral antibiotics dispensed and duration explained
- Advice on expected recovery (fatigue can last 6 weeks)
- GP follow-up and 6-week CXR arranged
- Smoking cessation if applicable
- Pneumococcal and influenza vaccination offered (if eligible)
Frequently Asked Questions
"What is the difference between lobar and bronchopneumonia on CXR?"
Lobar pneumonia shows dense homogeneous consolidation confined to a single lobe with air bronchograms — typically caused by Streptococcus pneumoniae. Bronchopneumonia shows patchy, bilateral, multilobar consolidation centred around the bronchial tree — typically caused by Staphylococcus aureus, Haemophilus influenzae, or atypical organisms. The distinction can guide antibiotic selection but both may look similar clinically.
"Why does pneumonia cause hyponatraemia?"
Hyponatraemia in pneumonia has two main mechanisms: SIADH (inappropriate ADH secretion triggered by pulmonary inflammation — dilutional hyponatraemia) and hypovolaemia (poor intake, fever-related fluid losses — relative sodium deficit). SIADH is especially associated with Legionella and pneumococcal pneumonia. It usually resolves with treatment of the pneumonia. Hyponatraemia in pneumonia is associated with more severe disease and slower recovery.
"When should you use the CURB-65 score versus the PSI?"
CURB-65 is simpler, quicker, and more widely used in UK clinical practice. The Pneumonia Severity Index (PSI) includes 20 variables and more accurately risk-stratifies low-risk patients — useful for identifying patients safe for outpatient management. In UK OSCEs, CURB-65 is the expected tool. Both tools can under-triage younger patients with significant pneumonia who score low due to age.
"What is hospital-acquired pneumonia (HAP) and how does management differ?"
HAP is pneumonia developing 48 or more hours after hospital admission. It is caused by different (often resistant) organisms: MRSA, Pseudomonas aeruginosa, Enterobacteriales, Acinetobacter. Treatment: broad-spectrum agents (co-amoxiclav IV + gentamicin, or piperacillin-tazobactam) — guided by local microbiological data. Ventilator-associated pneumonia (VAP) is HAP in mechanically ventilated patients and carries very high mortality.
"What is aspiration pneumonia and who is at risk?"
Aspiration pneumonia results from inhalation of oropharyngeal or gastric contents. Risk factors: reduced conscious level (post-seizure, intoxication, post-anaesthetic), dysphagia (stroke, bulbar palsy, dementia, achalasia), NG tube feeding, poor dentition. It classically affects dependent lung segments (right lower lobe in upright, posterior segments in supine). Often polymicrobial including anaerobes — cover with co-amoxiclav or metronidazole plus amoxicillin. SALT assessment for dysphagia before oral intake is resumed.
Related Posts
- Chest X-Ray Interpretation OSCE — identifying consolidation, effusions, and complications on CXR
- Respiratory Examination OSCE — examining the chest for signs of consolidation
- Sepsis and NEWS Score OSCE — recognising and managing pneumonia-associated sepsis