Recurrent Chest Infections

Clinical Vignette

A 30-year-old man presents with a persistent productive cough and recurrent respiratory infections since childhood. He reports large amounts of thick sputum daily and occasional haemoptysis. Please examine his respiratory system.

Positive Findings

  • General: Sputum pot at the bedside with thick, dark-green sputum. Signs of cachexia and mild dyspnoea.
  • Peripheral: Finger clubbing.
  • Chest: Coarse bilateral inspiratory crackles and occasional wheeze, with increased respiratory effort.
  • Additional Clues: Libre© device on upper arm.

Relevant Negative Findings

  • No evidence of cyanosis or asterixis.
  • No evidence of cor pulmonale.
  • No evidence of situs inversus or significant previous surgeries (e.g. lung resections).

What is the most likely diagnosis?

Cystic Fibrosis (CF) with bronchiectasis

What is your differential diagnosis?

  • Primary Ciliary Dyskinesia (PCD) – Considered if recurrent sinus infections or situs inversus were present.
  • Bronchiectasis secondary to postinfective causes – Recurrent childhood infections could lead to bronchiectasis, though CF remains more likely given the systemic features.
  • Allergic Bronchopulmonary Aspergillosis (ABPA) – May present with recurrent infections and productive cough but is usually associated with asthma.
  • Alpha-1 Antitrypsin Deficiency – Possible cause if emphysematous changes were present, particularly in younger patients, but less likely without a smoking history.

How would you investigate this patient?

  • Primary Testing for Cystic Fibrosis:
    • Sweat chloride test (Gold standard for CF diagnosis): Chloride levels >60 mmol/L on two occasions confirm CF.
    • CFTR genetic mutation analysis: To identify specific mutations (e.g., ΔF508) if sweat testing is equivocal.
  • Further Testing for Lung Involvement:
    • High-resolution CT (HRCT): Confirms bronchiectasis with "signet ring" appearance and bronchial wall thickening.
    • Spirometry: Expected to show an obstructive pattern, typical in CF-related lung disease (FEV1/FVC ratio < 0.7).
    • Sputum culture: For pathogens such as Pseudomonas aeruginosa, Staphylococcus aureus, and Burkholderia cepacia, which are commonly associated with CF.
  • Additional Investigations for Complications and Associated Conditions:
    • Immunoglobulin levels: To rule out immunodeficiency as a cause for recurrent infections.
    • Aspergillus serology: To check for ABPA, which is a common complication in CF patients.
    • Nutritional status assessment: Malabsorption is common in CF due to pancreatic insufficiency.
    • Diabetes screening: CF-related diabetes is a known complication.

How would you manage this patient?

  • Airway Clearance and Physiotherapy:
    • Specialist physiotherapy: Daily airway clearance with postural drainage, active cycle breathing, and oscillating PEP devices to mobilise secretions.
    • Nebulised saline: Helps increase sputum yield and ease expectoration.
  • Pharmacological Management:
    • Antibiotics:
      • Treat acute infections with broad-spectrum antibiotics targeting CF pathogens (Pseudomonas aeruginosa, S. aureus).
      • Long-term nebulised antibiotics (e.g. tobramycin) and low-dose oral macrolides (e.g. azithromycin) to prevent exacerbations.
    • Mucolytics: Nebulised agents such as DNase (dornase alfa) to reduce sputum viscosity.
    • Bronchodilators: If there is airflow limitation or concurrent asthma.
  • Nutritional and Supportive Care:
    • Pancreatic enzyme replacement (e.g., pancrelipase) for malabsorption.
    • Fat-soluble vitamins (A, D, E, K) supplementation.
    • Calorie-dense diet to counteract weight loss and support respiratory function.
  • Specialised and Long-term Interventions:
    • Regular monitoring for complications such as CF-related diabetes, liver disease, and bone disease.
    • Consideration for lung transplantation in advanced cases with severe lung function decline.

Viva Questions

  • What is Cystic Fibrosis (CF)?
    • An autosomal recessive disorder caused by mutations in the CFTR gene, leading to defective chloride transport and thick, sticky mucus in various organs, particularly the lungs and pancreas.
  • How is CF diagnosed?
    • Primarily via the sweat chloride test and genetic testing for CFTR mutations. Elevated chloride in sweat (>60 mmol/L) is diagnostic.
  • What pathogens commonly colonise the lungs in CF?
    • Pseudomonas aeruginosa, Staphylococcus aureus, and Burkholderia cepacia, which cause frequent and chronic lung infections.
  • What are the complications associated with CF?
    • Respiratory: Bronchiectasis, cor pulmonale, pneumothorax.
    • Gastrointestinal: Pancreatic insufficiency, CF-related diabetes, liver disease, distal intestinal obstruction syndrome (DIOS).
    • Reproductive: Male infertility (obstructive azoospermia).
  • What are the principles of managing lung disease in CF?
    • Airway clearance, infection control (long-term antibiotics), use of mucolytics, bronchodilators if airflow limitation is present, and addressing nutritional needs.
  • When is lung transplantation considered in CF?
    • Typically in end-stage lung disease with severe FEV1 decline, frequent exacerbations, or complications like cor pulmonale, often as a life-extending option.
  • Why is regular sputum culture important in CF management?
    • To identify specific pathogens and tailor antibiotic treatment, especially as Pseudomonas and other CF pathogens can develop resistance, making regular culture essential for managing infections effectively.