Lobar Pneumonia

Pneumonia in which inflammatory exudate fills an entire lobe, or most of one, with sparing of the airways. It is the classic pattern of pneumococcal infection and describes anatomy, not a single organism.

• About 90% of classic lobar pneumonia is Streptococcus pneumoniae. Others: Klebsiella pneumoniae (upper lobe with a bulging fissure), Legionella pneumophila, Haemophilus influenzae, Staphylococcus aureus, Streptococcus pyogenes and Mycobacterium tuberculosis (tuberculous lobar pneumonia).
• Pathological stages: congestion (days 1 to 2, vascular engorgement), red hepatisation (days 2 to 4, red cells and neutrophils fill the alveoli), grey hepatisation (days 4 to 8, fibrin and degenerating cells), resolution (days 8 to 21, enzymatic clearance). Antibiotics usually prevent the full sequence.
• Mortality is about 5 to 15% in admitted patients and about 20% when bacteraemic. Risk factors: age over 65, alcohol misuse, diabetes, COPD, HIV, asplenia, chronic kidney or liver disease, smoking, recent influenza and malnutrition.

• Abrupt onset with rigors, high fever, pleuritic chest pain, productive cough with rust coloured sputum, dyspnoea and often herpes labialis. Elderly patients may present with confusion or falls only.
• Signs: dullness to percussion, bronchial breathing, increased vocal resonance, whispering pectoriloquy, crackles, pleural rub, tachypnoea, tachycardia, hypoxaemia.
• Differential diagnosis: pulmonary infarction, lung cancer with post-obstructive collapse or consolidation, tuberculosis, pulmonary haemorrhage, organising pneumonia, eosinophilic pneumonia, mucinous adenocarcinoma, lung contusion and atelectasis.
• Complications: parapneumonic effusion and empyema (about 5 to 10%), lung abscess, pericarditis, meningitis, endocarditis, septic arthritis, septic shock, respiratory failure, ARDS, delayed resolution, and organising pneumonia.

• Chest X-ray: homogeneous opacity limited by a fissure, with air bronchograms and no volume loss. A lobar opacity with volume loss (fissure shift, raised diaphragm) suggests an obstructing lesion, so look for tumour, mucus plug or foreign body.
• Blood tests: full blood count, CRP, procalcitonin, urea and electrolytes, creatinine, liver function, glucose, lactate if septic, HIV test, two sets of blood cultures before antibiotics.
• Microbiology: sputum Gram stain and culture, pneumococcal and Legionella urinary antigens, respiratory viral PCR, Xpert MTB/RIF on sputum when cough lasts more than 2 weeks, in HIV, or in endemic settings.
• Pleural ultrasound and aspiration if an effusion is more than 10 mm. CT chest for failure to respond by 72 hours, suspected abscess, suspected obstruction, or an opacity persisting at 6 weeks.
• Severity scoring (one point each): confusion, urea greater than 7 mmol/L, respiratory rate 30 or more, systolic pressure less than 90 mmHg or diastolic 60 mmHg or less, age 65 or more. A score of 0 or 1 allows home treatment, 2 means admission, and 3 or more is severe.

• Give the first antibiotic dose within 1 hour in severe disease or sepsis and within 4 hours otherwise.
• Low severity, home treatment:
  • Amoxicillin 500 mg to 1 g orally three times daily for 5 days.
  • Penicillin allergy: doxycycline 200 mg on day 1 then 100 mg twice daily, or clarithromycin 500 mg twice daily, for 5 days.
• Moderate severity, admitted:
  • Benzylpenicillin 1.2 g (2 million units) IV every 4 to 6 hours, or amoxicillin 1 g IV or orally three times daily, plus clarithromycin 500 mg twice daily (or doxycycline 100 mg twice daily) for 7 days. Switch to oral when stable.
• Severe:
  • Ceftriaxone 2 g IV daily (or co-amoxiclav 1.2 g IV three times daily) plus clarithromycin 500 mg IV twice daily or azithromycin 500 mg daily.
  • Penicillin allergy: levofloxacin 750 mg IV daily plus a macrolide when Legionella is possible.
  • Add vancomycin 15 to 20 mg/kg IV every 8 to 12 hours (trough 15 to 20 mg/L) when Staphylococcus aureus is likely.
  • Hydrocortisone 200 mg/day IV (50 mg every 6 hours) for up to 7 days in severe pneumonia with respiratory failure or shock (evidence is moderate; avoid in influenza).
• Duration: 5 days if afebrile for 48 hours and stable; 7 to 10 days for bacteraemic disease; 14 days or more for empyema, abscess, Staphylococcus aureus or extrapulmonary spread; Legionella 7 to 14 days.
• Supportive care: oxygen to SpO2 94 to 98% (88 to 92% in COPD with carbon dioxide retention), IV fluids, paracetamol 1 g four times daily, enoxaparin 40 mg SC daily, early mobilisation, smoking cessation with nicotine patch 21 mg/24 h.
• Parapneumonic effusion more than 10 mm: diagnostic aspiration; place a chest drain for pus, pH less than 7.2, glucose less than 2.2 mmol/L or a positive culture, with intrapleural alteplase 10 mg plus dornase alfa 5 mg twice daily for 3 days when loculated.
• Failure to improve at 72 hours: confirm the diagnosis, check cultures, exclude empyema, abscess, tuberculosis and obstruction, and broaden cover.
• Persisting lobar opacity at 6 to 12 weeks: CT chest and bronchoscopy to exclude cancer, tuberculosis and organising pneumonia. For organising pneumonia give prednisolone 0.5 to 1 mg/kg/day for 4 to 6 weeks, then tapered slowly to a total course of 6 to 12 months.
• Special groups:
  • Children: amoxicillin 40 to 50 mg/kg per dose twice daily for 5 days; ampicillin 50 mg/kg IV every 6 hours or ceftriaxone 50 to 100 mg/kg/day (maximum 4 g) if severe.
  • Pregnancy: amoxicillin or ceftriaxone with azithromycin 500 mg daily; avoid doxycycline and fluoroquinolones; keep maternal SpO2 greater than 95%.
  • Elderly: lower threshold for admission, watch for delirium, review swallowing.
  • Renal impairment: adjust vancomycin, levofloxacin and penicillin doses.
  • HIV: test for tuberculosis and Pneumocystis pneumonia; co-trimoxazole 960 mg daily prophylaxis when CD4 count is less than 200.
• Prevention: pneumococcal conjugate vaccine (20-valent single dose, or 15-valent followed by 23-valent polysaccharide vaccine 8 weeks or more later) for adults 65 or older and those with chronic disease or HIV; yearly influenza vaccine.
• Red flags: respiratory rate 30 or more, SpO2 less than 90%, confusion, hypotension, large effusion, volume loss on imaging, no response at 72 hours.
• Follow up: review at 48 to 72 hours and at 6 weeks; repeat chest X-ray at 6 weeks in smokers over 50.