How should recurrent chest infections be evaluated and managed in an adult patient?

Evaluation and Management of Recurrent Chest Infections in Adults

Adults with recurrent chest infections require systematic investigation for bronchiectasis as the primary underlying diagnosis, confirmed by thin-section CT chest imaging, followed by comprehensive etiologic workup including immunodeficiency screening, sputum microbiology, and assessment for structural abnormalities.

Initial Diagnostic Approach

Clinical Threshold for Investigation

Investigate for bronchiectasis in any patient with persistent mucopurulent or purulent sputum production, particularly with relevant risk factors. 1 The British Thoracic Society specifically defines the population requiring investigation as those with chronic productive cough or experiencing two or more chest infections annually. 1

Imaging Protocol

• Obtain baseline chest X-ray initially, but this is insufficient for diagnosis. 1
• Perform thin-section CT chest (the gold standard) to confirm bronchiectasis when clinically suspected. 1 CT should be obtained during clinically stable disease for optimal diagnostic accuracy and serial comparison. 1
• CT diagnostic criteria include: bronchoarterial ratio >1, lack of bronchial tapering, or airway visibility within 1cm of pleural surface. 1

Essential Laboratory Investigations

All patients require the following baseline workup: 1

• Full blood count, serum total IgE, and Aspergillus-specific IgE or skin prick testing to exclude allergic bronchopulmonary aspergillosis (ABPA). 1
• Serum IgG, IgA, and IgM levels to screen for immunodeficiency. 1
• Baseline pneumococcal capsular polysaccharide antibody levels in all patients; if low, immunize with 23-valent pneumococcal vaccine and retest 4-8 weeks later to assess specific antibody deficiency. 1
• Sputum cultures for routine and mycobacterial organisms while clinically stable. 1

Specialized Testing Based on Clinical Features

Consider primary ciliary dyskinesia (PCD) testing when: 2

• Nasal nitric oxide measurement as initial screening (cutoff <30 nL/min has 91% sensitivity, 96% specificity). 2
• High-speed video microscopy of ciliary beat frequency if nasal nitric oxide abnormal (100% sensitivity, 93% specificity). 2
• Transmission electron microscopy when video microscopy shows abnormalities (79% sensitivity, 100% specificity). 2

Bronchoscopy is indicated for: 1

• Localized disease to exclude endobronchial lesion or foreign body. 1
• Bronchial aspiration/wash targeting CT-identified bronchiectasis areas in non-expectorating patients, particularly helpful for diagnosing non-tuberculous mycobacterial disease. 1

High-Risk Populations Requiring Investigation

Specific patient groups warrant lower threshold for bronchiectasis investigation: 1

• Rheumatoid arthritis patients with chronic productive cough or recurrent infections. 1
• COPD patients with ≥2 exacerbations annually and positive Pseudomonas aeruginosa sputum culture while stable. 1
• Inflammatory bowel disease patients with chronic productive cough. 1
• Immunosuppressed patients (HIV, transplant recipients, lymphoma/vasculitis treatment history) with chronic productive cough. 1
• Chronic rhinosinusitis patients with lower respiratory symptoms. 1

Management of Confirmed Bronchiectasis

Airway Clearance

Respiratory physiotherapy is foundational and must be taught by a specialist respiratory physiotherapist. 1 Patients should receive education about their condition and advice on adjuncts (inhaled/oral therapy or exercise) to enhance airway clearance effectiveness. 1

Antibiotic Strategies

For acute exacerbations: 3

• Empiric antibiotics should cover Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, and Staphylococcus aureus. 3
• Minimum 5-day antibiotic course for community-acquired pneumonia. 3

For chronic Pseudomonas aeruginosa colonization with frequent exacerbations: 1

• Macrolide antibiotics (such as azithromycin) have demonstrated benefit as anti-inflammatory treatment. 1
• Inhaled antibiotics show small effect in adults with non-cystic fibrosis bronchiectasis. 1

Adjunctive Therapies During Exacerbations

Positive expiratory pressure (PEP) therapy is the optimal airway clearance modality as it maintains malacic airways open while promoting secretion removal. 1 Conventional percussion and postural drainage offer no advantage over PEP techniques. 1 Avoid head-down percussion and postural drainage as these promote gastroesophageal reflux. 1

Nebulized hypertonic saline shows small benefits in improving lung function and sputum burden even without bronchiectasis. 1

Specialized Considerations

Aspiration and Reflux Assessment

Investigate reflux and aspiration only in symptomatic patients or those with suggestive clinical features. 1 Recurrent infections may indicate silent aspiration requiring bulbar function assessment and speech-language pathology referral. 1

Geographic Considerations

In endemic areas (southwestern United States), consider coccidioidomycosis in patients failing antibiotic therapy. 4 Use serum antibody testing as initial diagnostic test, but employ multiple complementary approaches simultaneously including urine/serum antigen testing and sputum culture. 4

Follow-Up and Monitoring

Patients requiring secondary care follow-up include those with: 1

• Chronic Pseudomonas aeruginosa, non-tuberculous mycobacteria, or MRSA colonization. 1
• Deteriorating bronchiectasis (significant symptom deterioration, unexpected increased exacerbation frequency/severity, frequent admissions, early relapse after treatment, or rapid lung function decline). 1

Consider using the bronchiectasis severity index to guide management decisions. 1

Critical Pitfalls to Avoid

• Do not delay investigation for years while treating individual pneumonia episodes when clinical features suggest underlying structural disease. 2 Early diagnosis is essential to prevent progressive or irreversible lung damage. 5
• Do not assume normal vital signs and lung examination exclude pneumonia—isolated auscultatory findings without systemic features do not warrant routine antibiotics. 3
• Do not overlook immunodeficiency screening—this is mandatory in all patients with recurrent infections. 1
• Do not perform repeat bronchoscopy while on antibiotics for diagnostic purposes as this has high false-negative rates. 2